[v2,3/7] kernel-shark-qt: Introduce the visualization model used by the Qt-based KS

Commit Message

Yordan Karadzhov July 31, 2018, 1:52 p.m. UTC

The model, used by the Qt-based KernelShark for visualization of trace data
is build over the concept of "Data Bins". When visualizing a large data-set
of trace records, we are limited by the number of screen pixels available for
drawing. The model divides the data-set into data-units, also called Bins.
The Bin has to be defined in such a way that the entire content of one Bin
can be summarized and visualized by a single graphical element.
This model uses the timestamp of the trace records, as a criteria for forming
Bins. When the Model has to visualize all records inside a given time-window,
it divides this time-window into N smaller, uniformly sized subintervals and
then defines that one Bin contains all trace records, having timestamps
falling into one of this subintervals. Because the model operates over an
array of trace records, sorted in time, the content of each Bin can be
retrieved by simply knowing the index of the first element inside this Bin
and the index of the first element of the next Bin. This means that knowing
the index of the first element in each Bin is enough to determine the State
of the model.

The State of the model can be modified by its five basic operations: Zoon-In,
Zoom-Out, Shift-Forward, Shift-Backward and Jump-To. After each of these
operations, the new State of the model is retrieved, by using binary search
to find the index of the first element in each Bin. This means that each one
of the five basic operations of the model has log(n) time complexity (see
previous change log).

In order to keep the visualization of the new state of the model as efficient
as possible, the model needs a way to summarize and visualize the content of
the Bins in constant time. This is achieved by limiting ourself to only
checking the content of the records at the beginning and at the end of the
Bin. As explaned in the previous change log, this approach has the very
counter-intuitive effect of making the update of the sparse (or empty) Graphs
much slower. The problem of the Sparse Graphs will be addressed in another
patch, where "Data Collections" will be introduced.

Signed-off-by: Yordan Karadzhov (VMware) <[e-mail]>
---
 kernel-shark-qt/src/CMakeLists.txt    |    3 +-
 kernel-shark-qt/src/libkshark-model.c | 1135 +++++++++++++++++++++++++
 kernel-shark-qt/src/libkshark-model.h |  142 ++++
 3 files changed, 1279 insertions(+), 1 deletion(-)
 create mode 100644 kernel-shark-qt/src/libkshark-model.c
 create mode 100644 kernel-shark-qt/src/libkshark-model.h

Comments

Steven Rostedt Aug. 1, 2018, 12:51 a.m. UTC | #1

On Tue, 31 Jul 2018 16:52:44 +0300
"Yordan Karadzhov (VMware)" <[e-mail]> wrote:

> diff --git a/kernel-shark-qt/src/CMakeLists.txt b/kernel-shark-qt/src/CMakeLists.txt
> index ed3c60e..ec22f63 100644
> --- a/kernel-shark-qt/src/CMakeLists.txt
> +++ b/kernel-shark-qt/src/CMakeLists.txt
> @@ -1,7 +1,8 @@
>  message("\n src ...")
>  
>  message(STATUS "libkshark")
> -add_library(kshark SHARED libkshark.c)
> +add_library(kshark SHARED libkshark.c
> +                          libkshark-model.c)
>  
>  target_link_libraries(kshark ${CMAKE_DL_LIBS}
>                               ${TRACEEVENT_LIBRARY}
> diff --git a/kernel-shark-qt/src/libkshark-model.c b/kernel-shark-qt/src/libkshark-model.c
> new file mode 100644
> index 0000000..4a4e910
> --- /dev/null
> +++ b/kernel-shark-qt/src/libkshark-model.c
> @@ -0,0 +1,1135 @@
> +// SPDX-License-Identifier: LGPL-2.1
> +
> +/*
> + * Copyright (C) 2017 VMware Inc, Yordan Karadzhov <[e-mail]>
> + */
> +
> + /**
> +  *  @file    libkshark.c
> +  *  @brief   Visualization model for FTRACE (trace-cmd) data.
> +  */
> +
> +// C
> +#include <stdlib.h>
> +
> +// KernelShark
> +#include "libkshark-model.h"
> +

Needs comment here explaining what these are.

> +#define UOB(histo) (histo->n_bins)
> +#define LOB(histo) (histo->n_bins + 1)

Perhaps add:

/* For all bins */
# define ALLB(histo) LOB(histo)

> +
> +/**
> + * @brief Initialize the Visualization model.
> + * @param histo: Input location for the model descriptor.
> + */
> +void ksmodel_init(struct kshark_trace_histo *histo)
> +{
> +	/*
> +	 * Initialize an empty histo. The histo will have no bins and will
> +	 * contain no data.
> +	 */
> +	histo->bin_size = 0;
> +	histo->min = 0;
> +	histo->max = 0;
> +	histo->n_bins = 0;
> +
> +	histo->bin_count = NULL;
> +	histo->map = NULL;
> +}
> +
> +/**
> + * @brief Clear (reset) the Visualization model.
> + * @param histo: Input location for the model descriptor.
> + */
> +void ksmodel_clear(struct kshark_trace_histo *histo)
> +{
> +	/* Reset the histo. It will have no bins and will contain no data. */
> +	free(histo->map);
> +	free(histo->bin_count);
> +	ksmodel_init(histo);
> +}
> +
> +static void ksmodel_reset_bins(struct kshark_trace_histo *histo,
> +			       size_t first, size_t last)
> +{
> +	/* Reset the content of the bins. */
> +	memset(&histo->map[first], KS_EMPTY_BIN,
> +	       (last - first + 1) * sizeof(histo->map[0]));

This patch should add a comment here and by KS_EMPTY_BIN stating that
KS_EMPTY_BIN is expected to be -1, as it is used to reset the entire
array with memset(). As memset() only updates an array to a single
byte, that byte must be the same throughout. Which works for zero and
-1.

> +
> +	memset(&histo->bin_count[first], 0,
> +	       (last - first + 1) * sizeof(histo->bin_count[0]));
> +}
> +
> +static bool ksmodel_histo_alloc(struct kshark_trace_histo *histo, size_t n)
> +{
> +	free(histo->bin_count);
> +	free(histo->map);
> +
> +	/* Create bins. Two overflow bins are added. */
> +	histo->map = calloc(n + 2, sizeof(*histo->map));
> +	histo->bin_count = calloc(n + 2, sizeof(*histo->bin_count));
> +
> +	if (!histo->map || !histo->bin_count) {
> +		ksmodel_clear(histo);
> +		fprintf(stderr, "Failed to allocate memory for a histo.\n");
> +		return false;
> +	}
> +
> +	histo->n_bins = n;
> +
> +	return true;
> +}
> +
> +static void ksmodel_set_in_range_bining(struct kshark_trace_histo *histo,
> +					size_t n, uint64_t min, uint64_t max,
> +					bool force_in_range)
> +{
> +	uint64_t corrected_range, delta_range, range = max - min;
> +	struct kshark_entry *last;
> +
> +	/* The size of the bin must be >= 1, hence the range must be >= n. */
> +	if (n == 0 || range < n)
> +		return;
> +
> +	/*
> +	 * If the number of bins changes, allocate memory for the descriptor
> +	 * of the model.
> +	 */
> +	if (n != histo->n_bins) {
> +		if (!ksmodel_histo_alloc(histo, n)) {
> +			ksmodel_clear(histo);
> +			return;
> +		}
> +	}
> +
> +	/* Reset the content of all bins (including overflow bins) to zero. */
> +	ksmodel_reset_bins(histo, 0, histo->n_bins + 1);

Here we could then have:

	ksmodel_reset_bins(histo, 0, ALLB(histo));

> +
> +	if (range % n == 0) {
> +		/*
> +		 * The range is multiple of the number of bin and needs no
> +		 * adjustment. This is very unlikely to happen but still ...
> +		 */
> +		histo->min = min;
> +		histo->max = max;
> +		histo->bin_size = range / n;
> +	} else {
> +		/*
> +		 * The range needs adjustment. The new range will be slightly
> +		 * bigger, compared to the requested one.
> +		 */
> +		histo->bin_size = range / n + 1;
> +		corrected_range = histo->bin_size * n;
> +		delta_range = corrected_range - range;
> +		histo->min = min - delta_range / 2;
> +		histo->max = histo->min + corrected_range;
> +
> +		if (!force_in_range)
> +			return;
> +
> +		/*
> +		 * Make sure that the new range doesn't go outside of the time
> +		 * interval of the dataset.
> +		 */
> +		last = histo->data[histo->data_size - 1];
> +		if (histo->min < histo->data[0]->ts) {
> +			histo->min = histo->data[0]->ts;
> +			histo->max = histo->min + corrected_range;
> +		} else if (histo->max > last->ts) {
> +			histo->max = last->ts;
> +			histo->min = histo->max - corrected_range;
> +		}

Hmm, Let's say the range of the data is 0..1,000,001 and we picked a
range of 999,999 starting at 0. And there's 1024 buckets. This would
have:

min = 0; max = 999999; n = 1024; range = 999999;

bin_size = 999999 / 1024 + 1 = 977;
correct_range = 977 * 1024 = 1000448;
delta_rang = 1000448 - 999999 = 449;
histo->min = 0 - 449 / 2 = -224;
histo->max = -224 + 1000448 = 1000224;

Now histo->min (-224) < histo->data[0]->ts (0) so

histo->min = 0;
histo->max = 0 + 1000448 = 1000448;

Thus we get max greater than the data set.

Actually, we would always get a range greater than the data set, if the
data set itself is not divisible by the bin size. This that a problem?

-- Steve

> +	}
> +}
> +
> +/**
> + * @brief Prepare the bining of the Visualization model.
> + * @param histo: Input location for the model descriptor.
> + * @param n: Number of bins.
> + * @param min: Lower edge of the time-window to be visualized.
> + * @param max: Upper edge of the time-window to be visualized.
> + */
> +void ksmodel_set_bining(struct kshark_trace_histo *histo,
> +			size_t n, uint64_t min, uint64_t max)
> +{
> +	ksmodel_set_in_range_bining(histo, n, min, max, false);
> +}
> +
>

Steven Rostedt Aug. 1, 2018, 1:43 a.m. UTC | #2

On Tue, 31 Jul 2018 16:52:44 +0300
"Yordan Karadzhov (VMware)" <[e-mail]> wrote:

> +static void ksmodel_set_next_bin_edge(struct kshark_trace_histo *histo,
> +				      size_t bin)
> +{
> +	size_t time, row, next_bin = bin + 1;
> +
> +	/* Calculate the beginning of the next bin. */
> +	time = histo->min + next_bin * histo->bin_size;
> +
> +	/*
> +	 * Find the index of the first entry inside
> +	 * the next bin (timestamp > time).
> +	 */
> +	row = kshark_find_entry_by_time(time, histo->data, 0,
> +					histo->data_size - 1);

Hmm, I see this used as this:

       for (bin = 0; bin < histo->n_bins; ++bin)
               ksmodel_set_next_bin_edge(histo, bin);

A lot. Thus we should be able to optimize this with:

static void ksmodel_set_next_bin_edge(struct kshark_trace_histo *histo,
				size_t bin, size_t *last_row)
{

	row = kshark_find_entry_by_time(time, histo->data, *last_row,
					histo->data_size - 1);

	*last_row = row;

And the caller can be:

	last_row = 0;
	for (bin = 0; bin < histo->n_bins; ++bin)
		ksmodel_set_next_bin_edge(histo, bin, &last_row);

Then we wont be doing the search from 0 each time. It should help speed
it up a little.

> +
> +	/*
> +	 * The timestamp of the very last entry of the dataset can be exactly
> +	 * equal to the value of the upper edge of the range. This is very
> +	 * likely to happen when we use ksmodel_set_in_range_bining(). In this
> +	 * case we have to increase the size of the very last bin in order to
> +	 * make sure that the last entry of the dataset will fall into it.
> +	 */
> +	if (next_bin == histo->n_bins - 1)
> +		++time;
> +
> +	if (histo->data[row]->ts >= time + histo->bin_size) {
> +		/* The bin is empty. */
> +		histo->map[next_bin] = KS_EMPTY_BIN;
> +		return;
> +	}
> +
> +	/* Set the index of the first entry. */
> +	histo->map[next_bin] = row;
> +}
> +


[..]

> +/**
> + * @brief Provide the Visualization model with data. Calculate the current
> + *	  state of the model.
> + * @param histo: Input location for the model descriptor.
> + * @param data: Input location for the trace data.
> + * @param n: Number of bins.
> + */
> +void ksmodel_fill(struct kshark_trace_histo *histo,
> +		  struct kshark_entry **data, size_t n)
> +{
> +	int bin;
> +
> +	histo->data_size = n;
> +	histo->data = data;
> +
> +	if (histo->n_bins == 0 ||
> +	    histo->bin_size == 0 ||
> +	    histo->data_size == 0) {
> +		/*
> +		 * Something is wrong with this histo.
> +		 * Most likely the binning is not set.
> +		 */
> +		ksmodel_clear(histo);
> +		fprintf(stderr,
> +			"Unable to fill the model with data.\n");
> +		fprintf(stderr,
> +			"Try to set the bining of the model first.\n");
> +
> +		return;
> +	}
> +
> +	/* Set the Lower Overflow bin */
> +	ksmodel_set_lower_edge(histo);
> +
> +	/*
> +	 * Loop over the dataset and set the beginning of all individual bins.
> +	 */
> +	bin = 0;

Superfluous bin assignment above.

> +	for (bin = 0; bin < histo->n_bins; ++bin)
> +		ksmodel_set_next_bin_edge(histo, bin);
> +
> +	/* Set the Upper Overflow bin. */
> +	ksmodel_set_upper_edge(histo);
> +
> +	/* Calculate the number of entries in each bin. */
> +	ksmodel_set_bin_counts(histo);
> +}
> +
> +/**
> + * @brief Get the total number of entries in a given bin.
> + * @param histo: Input location for the model descriptor.
> + * @param bin: Bin id.
> + * @returns The number of entries in this bin.
> + */
> +size_t ksmodel_bin_count(struct kshark_trace_histo *histo, int bin)
> +{
> +	if (bin >= 0 && bin < histo->n_bins)
> +		return histo->bin_count[bin];
> +
> +	if (bin == UPPER_OVERFLOW_BIN)
> +		return histo->bin_count[UOB(histo)];
> +
> +	if (bin == LOWER_OVERFLOW_BIN)
> +		return histo->bin_count[LOB(histo)];
> +
> +	return 0;
> +}
> +
> +/**
> + * @brief Shift the time-window of the model forward. Recalculate the current
> + *	  state of the model.
> + * @param histo: Input location for the model descriptor.
> + * @param n: Number of bins to shift.
> + */
> +void ksmodel_shift_forward(struct kshark_trace_histo *histo, size_t n)
> +{
> +	int bin;
> +	
> +	if (!histo->data_size)
> +		return;
> +
> +	if (histo->bin_count[UOB(histo)] == 0) {
> +		/*
> +		 * The Upper Overflow bin is empty. This means that we are at
> +		 * the upper edge of the dataset already. Do nothing in this
> +		 * case.
> +		 */
> +		return;
> +	}
> +
> +	histo->min += n * histo->bin_size;
> +	histo->max += n * histo->bin_size;
> +
> +	if (n >= histo->n_bins) {
> +		/*
> +		 * No overlap between the new and the old ranges. Recalculate
> +		 * all bins from scratch. First calculate the new range.
> +		 */
> +		ksmodel_set_bining(histo, histo->n_bins, histo->min,
> +							 histo->max);
> +
> +		ksmodel_fill(histo, histo->data, histo->data_size);
> +		return;
> +	}
> +
> +	/* Set the new Lower Overflow bin. */
> +	ksmodel_set_lower_edge(histo);
> +
> +	/*
> +	 * Copy the the mapping indexes of all overlaping bins starting from
> +	 * bin "0" of the new histo. Note that the number of overlaping bins
> +	 * is histo->n_bins - n.
> +	 */
> +	memmove(&histo->map[0], &histo->map[n],
> +		sizeof(histo->map[0]) * (histo->n_bins - n));
> +
> +	/*
> +	 * The the mapping index pf the old Upper Overflow bin is now index

"The the" and "pf"?

> +	 * of the first new bin.
> +	 */
> +	bin = UOB(histo) - n;
> +	histo->map[bin] = histo->map[UOB(histo)];
> +
> +	/* Calculate only the content of the new (non-overlapping) bins. */
> +	for (; bin < histo->n_bins; ++bin)
> +		ksmodel_set_next_bin_edge(histo, bin);
> +
> +	/*
> +	 * Set the new Upper Overflow bin and calculate the number of entries
> +	 * in each bin.
> +	 */
> +	ksmodel_set_upper_edge(histo);
> +	ksmodel_set_bin_counts(histo);
> +}
> +
> +/**
> + * @brief Shift the time-window of the model backward. Recalculate the current
> + *	  state of the model.
> + * @param histo: Input location for the model descriptor.
> + * @param n: Number of bins to shift.
> + */
> +void ksmodel_shift_backward(struct kshark_trace_histo *histo, size_t n)
> +{
> +	int bin;
> +
> +	if (!histo->data_size)
> +		return;
> +
> +	if (histo->bin_count[LOB(histo)] == 0) {
> +		/*
> +		 * The Lower Overflow bin is empty. This means that we are at
> +		 * the Lower edge of the dataset already. Do nothing in this
> +		 * case.
> +		 */
> +		return;
> +	}
> +
> +	histo->min -= n * histo->bin_size;
> +	histo->max -= n * histo->bin_size;
> +
> +	if (n >= histo->n_bins) {
> +		/*
> +		 * No overlap between the new and the old range. Recalculate
> +		 * all bins from scratch. First calculate the new range.
> +		 */
> +		ksmodel_set_bining(histo, histo->n_bins, histo->min,
> +							 histo->max);
> +
> +		ksmodel_fill(histo, histo->data, histo->data_size);
> +		return;
> +	}
> +
> +	/*
> +	 * Copy the the mapping indexes of all overlaping bins starting from
> +	 * bin "0" of the old histo. Note that the number of overlaping bins
> +	 * is histo->n_bins - n.
> +	 */
> +	memmove(&histo->map[n], &histo->map[0],
> +		sizeof(histo->map[0]) * (histo->n_bins - n));
> +
> +	/* Set the new Lower Overflow bin. */
> +	ksmodel_set_lower_edge(histo);
> +
> +	/* Calculate only the content of the new (non-overlapping) bins. */
> +	bin = 0;
> +	while (bin < n) {

Convert this to a for loop please.

-- Steve

> +		ksmodel_set_next_bin_edge(histo, bin);
> +		++bin;
> +	}
> +
> +	/*
> +	 * Set the new Upper Overflow bin and calculate the number of entries
> +	 * in each bin.
> +	 */
> +	ksmodel_set_upper_edge(histo);
> +	ksmodel_set_bin_counts(histo);
> +}
>

Yordan Karadzhov Aug. 1, 2018, 4:10 p.m. UTC | #3

On 1.08.2018 03:51, Steven Rostedt wrote:
>> +static void ksmodel_set_in_range_bining(struct kshark_trace_histo *histo,
>> +					size_t n, uint64_t min, uint64_t max,
>> +					bool force_in_range)
>> +{
>> +	uint64_t corrected_range, delta_range, range = max - min;
>> +	struct kshark_entry *last;
>> +
>> +	/* The size of the bin must be >= 1, hence the range must be >= n. */
>> +	if (n == 0 || range < n)
>> +		return;
>> +
>> +	/*
>> +	 * If the number of bins changes, allocate memory for the descriptor
>> +	 * of the model.
>> +	 */
>> +	if (n != histo->n_bins) {
>> +		if (!ksmodel_histo_alloc(histo, n)) {
>> +			ksmodel_clear(histo);
>> +			return;
>> +		}
>> +	}
>> +
>> +	/* Reset the content of all bins (including overflow bins) to zero. */
>> +	ksmodel_reset_bins(histo, 0, histo->n_bins + 1);
> Here we could then have:
>
> 	ksmodel_reset_bins(histo, 0, ALLB(histo));
>
>> +
>> +	if (range % n == 0) {
>> +		/*
>> +		 * The range is multiple of the number of bin and needs no
>> +		 * adjustment. This is very unlikely to happen but still ...
>> +		 */
>> +		histo->min = min;
>> +		histo->max = max;
>> +		histo->bin_size = range / n;
>> +	} else {
>> +		/*
>> +		 * The range needs adjustment. The new range will be slightly
>> +		 * bigger, compared to the requested one.
>> +		 */
>> +		histo->bin_size = range / n + 1;
>> +		corrected_range = histo->bin_size * n;
>> +		delta_range = corrected_range - range;
>> +		histo->min = min - delta_range / 2;
>> +		histo->max = histo->min + corrected_range;
>> +
>> +		if (!force_in_range)
>> +			return;
>> +
>> +		/*
>> +		 * Make sure that the new range doesn't go outside of the time
>> +		 * interval of the dataset.
>> +		 */
>> +		last = histo->data[histo->data_size - 1];
>> +		if (histo->min < histo->data[0]->ts) {
>> +			histo->min = histo->data[0]->ts;
>> +			histo->max = histo->min + corrected_range;
>> +		} else if (histo->max > last->ts) {
>> +			histo->max = last->ts;
>> +			histo->min = histo->max - corrected_range;
>> +		}
> Hmm, Let's say the range of the data is 0..1,000,001 and we picked a
> range of 999,999 starting at 0. And there's 1024 buckets. This would
> have:
>
> min = 0; max = 999999; n = 1024; range = 999999;
>
> bin_size = 999999 / 1024 + 1 = 977;
> correct_range = 977 * 1024 = 1000448;
> delta_rang = 1000448 - 999999 = 449;
> histo->min = 0 - 449 / 2 = -224;
> histo->max = -224 + 1000448 = 1000224;
>
> Now histo->min (-224) < histo->data[0]->ts (0) so
>
> histo->min = 0;
> histo->max = 0 + 1000448 = 1000448;
>
> Thus we get max greater than the data set.
>
> Actually, we would always get a range greater than the data set, if the
> data set itself is not divisible by the bin size. This that a problem?
Hi Steven,
In your example you consider the case when we want to visualize the 
entire data-set.
Indeed in this case the true range of the histo will be slightly bigger. 
This is not a problem.

The "force_in_range" part of the logic in this function deals with 
another case.
Let's stick to your example but say that the current range is from 0 to 
10,000.
Now if the user hits the "Zoom Out" for a second, this function will be 
called several hundred times
and each call of the function will add its own small negative correction 
to the value of histo->min (initially 0).
At the end we will have a significant part of the graph outside of the 
data-set.

Thanks!
Yordan

>
> -- Steve
>
>> +	}
>> +}
>> +
>> +/**
>> + * @brief Prepare the bining of the Visualization model.
>> + * @param histo: Input location for the model descriptor.
>> + * @param n: Number of bins.
>> + * @param min: Lower edge of the time-window to be visualized.
>> + * @param max: Upper edge of the time-window to be visualized.
>> + */
>> +void ksmodel_set_bining(struct kshark_trace_histo *histo,
>> +			size_t n, uint64_t min, uint64_t max)
>> +{
>> +	ksmodel_set_in_range_bining(histo, n, min, max, false);
>> +}
>> +
>>

Steven Rostedt Aug. 1, 2018, 6:22 p.m. UTC | #4

On Tue, 31 Jul 2018 16:52:44 +0300
"Yordan Karadzhov (VMware)" <[e-mail]> wrote:


I'd add a comment above this function (yes static functions may have
header comments, just doesn't need to be doxygen like).

/*
 * Fill in the bin_count array, which maps the number of data rows that
 * exist within each bin.
 */

Or something like that.

> +static void ksmodel_set_bin_counts(struct kshark_trace_histo *histo)
> +{
> +	int i = 0, prev_not_empty;
> +
> +	memset(&histo->bin_count[0], 0,
> +	       (histo->n_bins) * sizeof(histo->bin_count[0]));
> +	/*
> +	 * Find the first bin which contains data. Start by checking the
> +	 * Lower Overflow bin.
> +	 */
> +	if (histo->map[histo->n_bins + 1] != KS_EMPTY_BIN) {

Hmm, shouldn't that be:

	if (histo->map[LOB(histo)] != KS_EMPTY_BIN) ?

> +		prev_not_empty = LOB(histo);
> +	} else {

Add a comment here:

		/* Find the first non-empty bin */

> +		while (histo->map[i] < 0) {

Can map[i] be a negative other than KS_EMPTY_BIN? 

> +			++i;
> +		}
> +
> +		prev_not_empty = i++;
> +	}
> +
> +	/*
> +	 * Starting from the first not empty bin, loop over all bins and fill
> +	 * in the bin_count array to hold the number of entries in each bin.
> +	 */
> +	while (i < histo->n_bins) {

The above should be a for loop:

	for (; i < histo->n_bins; i++) {


> +		if (histo->map[i] != KS_EMPTY_BIN) {
> +			/*
> +			 * Here we set the number of entries in
> +			 * "prev_not_empty" bin.

The above comment needs to be changed:

			/*
			 * The current bin is not empty, take its data
			 * row and subtract it from the data row of the
			 * previous not empty bin, which will give us
			 * the number of data rows in that bin.

Or something like that.

> +			 */
> +			histo->bin_count[prev_not_empty] =
> +				histo->map[i] - histo->map[prev_not_empty];
> +	
> +			prev_not_empty = i;
> +		}
> +
> +		++i;
> +	}
> +
> +	/* Check if the Upper Overflow bin contains data. */
> +	if (histo->map[UOB(histo)] == KS_EMPTY_BIN) {
> +		/*
> +		 * The Upper Overflow bin is empty. Use the size of the
> +		 * dataset to calculate the content of the previouse not
> +		 * empty bin.
> +		 */
> +		histo->bin_count[prev_not_empty] = histo->data_size -
> +						   histo->map[prev_not_empty];
> +	} else {
> +		/*
> +		 * Use the index of the first entry inside the Upper Overflow
> +		 * bin to calculate the content of the previouse not empty
> +		 * bin.
> +		 */
> +		histo->bin_count[prev_not_empty] = histo->map[UOB(histo)] -
> +						   histo->map[prev_not_empty];
> +	}
> +}
> +
> +/**
> + * @brief Provide the Visualization model with data. Calculate the current
> + *	  state of the model.
> + * @param histo: Input location for the model descriptor.
> + * @param data: Input location for the trace data.
> + * @param n: Number of bins.
> + */
> +void ksmodel_fill(struct kshark_trace_histo *histo,
> +		  struct kshark_entry **data, size_t n)
> +{
> +	int bin;
> +
> +	histo->data_size = n;
> +	histo->data = data;
> +
> +	if (histo->n_bins == 0 ||
> +	    histo->bin_size == 0 ||
> +	    histo->data_size == 0) {
> +		/*
> +		 * Something is wrong with this histo.
> +		 * Most likely the binning is not set.
> +		 */
> +		ksmodel_clear(histo);
> +		fprintf(stderr,
> +			"Unable to fill the model with data.\n");
> +		fprintf(stderr,
> +			"Try to set the bining of the model first.\n");
> +
> +		return;
> +	}
> +
> +	/* Set the Lower Overflow bin */
> +	ksmodel_set_lower_edge(histo);
> +
> +	/*
> +	 * Loop over the dataset and set the beginning of all individual bins.
> +	 */
> +	bin = 0;

As stated before, superfluous bin.

> +	for (bin = 0; bin < histo->n_bins; ++bin)
> +		ksmodel_set_next_bin_edge(histo, bin);
> +
> +	/* Set the Upper Overflow bin. */
> +	ksmodel_set_upper_edge(histo);
> +
> +	/* Calculate the number of entries in each bin. */
> +	ksmodel_set_bin_counts(histo);
> +}
> +
> +/**
> + * @brief Get the total number of entries in a given bin.
> + * @param histo: Input location for the model descriptor.
> + * @param bin: Bin id.
> + * @returns The number of entries in this bin.
> + */
> +size_t ksmodel_bin_count(struct kshark_trace_histo *histo, int bin)
> +{
> +	if (bin >= 0 && bin < histo->n_bins)
> +		return histo->bin_count[bin];
> +
> +	if (bin == UPPER_OVERFLOW_BIN)
> +		return histo->bin_count[UOB(histo)];
> +
> +	if (bin == LOWER_OVERFLOW_BIN)
> +		return histo->bin_count[LOB(histo)];
> +
> +	return 0;
> +}
> +
> +/**
> + * @brief Shift the time-window of the model forward. Recalculate the current
> + *	  state of the model.
> + * @param histo: Input location for the model descriptor.
> + * @param n: Number of bins to shift.
> + */
> +void ksmodel_shift_forward(struct kshark_trace_histo *histo, size_t n)
> +{
> +	int bin;
> +	
> +	if (!histo->data_size)
> +		return;
> +
> +	if (histo->bin_count[UOB(histo)] == 0) {

Or should this be:

	if (histo->map[UOB(histo)] == KS_EMPTY_BIN)  ?

I know it should mean the same, but we use map below, and I like to be
more consistent.

> +		/*
> +		 * The Upper Overflow bin is empty. This means that we are at
> +		 * the upper edge of the dataset already. Do nothing in this
> +		 * case.
> +		 */
> +		return;
> +	}
> +
> +	histo->min += n * histo->bin_size;
> +	histo->max += n * histo->bin_size;
> +
> +	if (n >= histo->n_bins) {
> +		/*
> +		 * No overlap between the new and the old ranges. Recalculate
> +		 * all bins from scratch. First calculate the new range.
> +		 */
> +		ksmodel_set_bining(histo, histo->n_bins, histo->min,
> +							 histo->max);
> +
> +		ksmodel_fill(histo, histo->data, histo->data_size);
> +		return;
> +	}
> +
> +	/* Set the new Lower Overflow bin. */
> +	ksmodel_set_lower_edge(histo);
> +

Hmm, the above also sets histo->map[0]. This should then equal
histo->map[n] right? I wonder if we should have a sanity check here
making sure that's the case.

> +	/*
> +	 * Copy the the mapping indexes of all overlaping bins starting from
> +	 * bin "0" of the new histo. Note that the number of overlaping bins
> +	 * is histo->n_bins - n.
> +	 */
> +	memmove(&histo->map[0], &histo->map[n],
> +		sizeof(histo->map[0]) * (histo->n_bins - n));
> +
> +	/*
> +	 * The the mapping index pf the old Upper Overflow bin is now index
> +	 * of the first new bin.
> +	 */
> +	bin = UOB(histo) - n;
> +	histo->map[bin] = histo->map[UOB(histo)];
> +
> +	/* Calculate only the content of the new (non-overlapping) bins. */
> +	for (; bin < histo->n_bins; ++bin)
> +		ksmodel_set_next_bin_edge(histo, bin);
> +
> +	/*
> +	 * Set the new Upper Overflow bin and calculate the number of entries
> +	 * in each bin.
> +	 */
> +	ksmodel_set_upper_edge(histo);
> +	ksmodel_set_bin_counts(histo);
> +}
> +
> +/**
> + * @brief Shift the time-window of the model backward. Recalculate the current
> + *	  state of the model.
> + * @param histo: Input location for the model descriptor.
> + * @param n: Number of bins to shift.
> + */
> +void ksmodel_shift_backward(struct kshark_trace_histo *histo, size_t n)
> +{
> +	int bin;
> +
> +	if (!histo->data_size)
> +		return;
> +
> +	if (histo->bin_count[LOB(histo)] == 0) {

Again, this probably should be:

	if (histo->map[LOB(histo)] == KS_EMPTY_BIN) {


> +		/*
> +		 * The Lower Overflow bin is empty. This means that we are at
> +		 * the Lower edge of the dataset already. Do nothing in this
> +		 * case.
> +		 */
> +		return;
> +	}
> +
> +	histo->min -= n * histo->bin_size;
> +	histo->max -= n * histo->bin_size;
> +
> +	if (n >= histo->n_bins) {
> +		/*
> +		 * No overlap between the new and the old range. Recalculate
> +		 * all bins from scratch. First calculate the new range.
> +		 */
> +		ksmodel_set_bining(histo, histo->n_bins, histo->min,
> +							 histo->max);
> +
> +		ksmodel_fill(histo, histo->data, histo->data_size);
> +		return;
> +	}
> +
> +	/*
> +	 * Copy the the mapping indexes of all overlaping bins starting from
> +	 * bin "0" of the old histo. Note that the number of overlaping bins
> +	 * is histo->n_bins - n.
> +	 */
> +	memmove(&histo->map[n], &histo->map[0],
> +		sizeof(histo->map[0]) * (histo->n_bins - n));
> +
> +	/* Set the new Lower Overflow bin. */
> +	ksmodel_set_lower_edge(histo);
> +
> +	/* Calculate only the content of the new (non-overlapping) bins. */
> +	bin = 0;
> +	while (bin < n) {

This needs to be a for loop.

> +		ksmodel_set_next_bin_edge(histo, bin);
> +		++bin;
> +	}
> +
> +	/*
> +	 * Set the new Upper Overflow bin and calculate the number of entries
> +	 * in each bin.
> +	 */
> +	ksmodel_set_upper_edge(histo);
> +	ksmodel_set_bin_counts(histo);
> +}
> +
> +/**
> + * @brief Move the time-window of the model to a given location. Recalculate
> + *	  the current state of the model.
> + * @param histo: Input location for the model descriptor.
> + * @param ts: position in time to be visualized.
> + */
> +void ksmodel_jump_to(struct kshark_trace_histo *histo, size_t ts)
> +{
> +	size_t min, max, range_min;
> +
> +	if (ts > histo->min && ts < histo->max) {
> +		/*
> +		 * The new position is already inside the range.
> +		 * Do nothing in this case.
> +		 */
> +		return;
> +	}
> +
> +	/*
> +	 * Calculate the new range without changing the size and the number
> +	 * of bins.
> +	 */
> +	min = ts - histo->n_bins * histo->bin_size / 2;
> +
> +	/* Make sure that the range does not go outside of the dataset. */
> +	if (min < histo->data[0]->ts)
> +		min = histo->data[0]->ts;
> +

I wonder if we should make this an else

	else {

> +	range_min = histo->data[histo->data_size - 1]->ts -
> +		   histo->n_bins * histo->bin_size;
> +
> +	if (min > range_min)
> +		min = range_min;

	}

Making sure min isn't less than the data set?

> +
> +	max = min + histo->n_bins * histo->bin_size;
> +
> +	/* Use the new range to recalculate all bins from scratch. */
> +	ksmodel_set_bining(histo, histo->n_bins, min, max);
> +	ksmodel_fill(histo, histo->data, histo->data_size);
> +}
> +
> +/**
> + * @brief Extend the time-window of the model. Recalculate the current state
> + *	  of the model.
> + * @param histo: Input location for the model descriptor.
> + * @param r: Scale factor of the zoom-out.
> + * @param mark: Focus point of the zoom-out.
> + */
> +void ksmodel_zoom_out(struct kshark_trace_histo *histo,
> +		      double r, int mark)
> +{
> +	size_t range, min, max, delta_min;
> +	double delta_tot;
> +
> +	if (!histo->data_size)
> +		return;
> +
> +	/*
> +	 * If the marker is not set, assume that the focal point of the zoom
> +	 * is the center of the range.
> +	 */
> +	if (mark < 0)
> +		mark = histo->n_bins / 2;
> +
> +	/*
> +	 * Calculate the new range of the histo. Use the bin of the marker
> +	 * as a focal point for the zoomout. With this the maker will stay
> +	 * inside the same bin in the new histo.
> +	 */
> +	range = histo->max - histo->min;
> +	delta_tot = range * r;
> +	delta_min = delta_tot * mark / histo->n_bins;
> +
> +	min = histo->min - delta_min;
> +	max = histo->max + (size_t) delta_tot - delta_min;

Took me a bit to figure out what exactly the above is doing. Let me
explain what I think it is doing and you can correct me if I'm wrong.

We set delta_tot to increase by the percentage requested (easy).

Now we make delta_min equal to a percentage of delta_tot based on where
mark is in the original bins. If mark is zero, then mark was at 0% of
the original bins, if it was at histo->n_bins - 1, it was at (almost)
100%. If it is half way, then we place delta_min at %50 of delta_tot.

Then we subtract the original min by the delta_tot * mark/n_bins
percentage, and add the max by delta_tot * (1 - mark/n_bins).

Sound right? Maybe we can add a comment saying such?

> +
> +	/* Make sure the new range doesn't go outside of the dataset. */
> +	if (min < histo->data[0]->ts)
> +		min = histo->data[0]->ts;
> +
> +	if (max > histo->data[histo->data_size - 1]->ts)
> +		max = histo->data[histo->data_size - 1]->ts;
> +
> +	/*
> +	 * Use the new range to recalculate all bins from scratch. Enforce
> +	 * "In Range" adjustment of the range of the model, in order to avoid
> +	 * slowly drifting outside of the data-set in the case when the very
> +	 * first or the very last entry is used as a focal point.
> +	 */
> +	ksmodel_set_in_range_bining(histo, histo->n_bins, min, max, true);
> +	ksmodel_fill(histo, histo->data, histo->data_size);
> +}
> +
> +/**
> + * @brief Shrink the time-window of the model. Recalculate the current state
> + *	  of the model.
> + * @param histo: Input location for the model descriptor.
> + * @param r: Scale factor of the zoom-in.
> + * @param mark: Focus point of the zoom-in.
> + */
> +void ksmodel_zoom_in(struct kshark_trace_histo *histo,
> +		     double r, int mark)
> +{
> +	size_t range, min, max, delta_min;
> +	double delta_tot;
> +
> +	if (!histo->data_size)
> +		return;
> +
> +	/*
> +	 * If the marker is not set, assume that the focal point of the zoom
> +	 * is the center of the range.
> +	 */
> +	if (mark < 0)
> +		mark = histo->n_bins / 2;
> +
> +	range = histo->max - histo->min;
> +
> +	/* Avoid overzooming. */
> +	if (range < histo->n_bins * 4)
> +		return;
> +
> +	/*
> +	 * Calculate the new range of the histo. Use the bin of the marker
> +	 * as a focal point for the zoomin. With this the maker will stay
> +	 * inside the same bin in the new histo.
> +	 */
> +	delta_tot =  range * r;
> +	if (mark == (int)histo->n_bins - 1)
> +		delta_min = delta_tot;


> +	else if (mark == 0)
> +		delta_min = 0;
> +	else
> +		delta_min = delta_tot * mark / histo->n_bins;

The above two are equivalent:

	if (mark == 0)
Then
	delta_min = delta_tot * mark / histo->n_bins = 0


> +
> +	min = histo->min + delta_min;
> +	max = histo->max - (size_t) delta_tot + delta_min;
> +
> +	/*
> +	 * Use the new range to recalculate all bins from scratch. Enforce
> +	 * "In Range" adjustment of the range of the model, in order to avoid
> +	 * slowly drifting outside of the data-set in the case when the very
> +	 * first or the very last entry is used as a focal point.
> +	 */
> +	ksmodel_set_in_range_bining(histo, histo->n_bins, min, max, true);
> +	ksmodel_fill(histo, histo->data, histo->data_size);
> +}

Hmm, I think zoom_out and zoom_in could be combined:

static void ksmodel_zoom(struct kshark_trace_histo *histo,
			 double r, int mark, bool zoom_in)
{
	size_t range, min, max, delta_min;
	double delta_tot;

	if (!histo->data_size)
		return;

	/*
	 * If the marker is not set, assume that the focal point of the zoom
	 * is the center of the range.
	 */
	if (mark < 0)
		mark = histo->n_bins / 2;

	range = histo->max - histo->min;

	/* Avoid overzooming. */
	if (range < histo->n_bins * 4)
		return;

	/*
	 * Calculate the new range of the histo. Use the bin of the marker
	 * as a focal point for the zoomout. With this the maker will stay
	 * inside the same bin in the new histo.
	 */
	delta_tot = range * r;
	if (mark == (int)histo->n_bins - 1)
		delta_min = delta_tot;
	else
		delta_min = delta_tot * mark / histo->n_bins;

	
	min = zoom_in ? histo->min + delta_min : histo->min - delta_min;
	max = zoom_in ? histo->max - (size_t) delta_tot + delta_min :
		        histo->max + (size_t) delta_tot - delta_min;


	/* Make sure the new range doesn't go outside of the dataset. */
	if (min < histo->data[0]->ts)
		min = histo->data[0]->ts;

	if (max > histo->data[histo->data_size - 1]->ts)
		max = histo->data[histo->data_size - 1]->ts;

	/*
	 * Use the new range to recalculate all bins from scratch. Enforce
	 * "In Range" adjustment of the range of the model, in order to avoid
	 * slowly drifting outside of the data-set in the case when the very
	 * first or the very last entry is used as a focal point.
	 */
	ksmodel_set_in_range_bining(histo, histo->n_bins, min, max, true);
	ksmodel_fill(histo, histo->data, histo->data_size);
}

void ksmodel_zoom_out(struct kshark_trace_histo *histo,
		      double r, int mark)
{
	ksmodel_zoom(histo, r, mark, false);
}

void ksmodel_zoom_in(struct kshark_trace_histo *histo,
		     double r, int mark)
{
	ksmodel_zoom(histo, r, mark, true);
}

-- Steve

Steven Rostedt Aug. 1, 2018, 6:44 p.m. UTC | #5

On Tue, 31 Jul 2018 16:52:44 +0300
"Yordan Karadzhov (VMware)" <[e-mail]> wrote:

> +/**
> + * @brief Get the index of the first entry in a given bin.
> + * @param histo: Input location for the model descriptor.
> + * @param bin: Bin id.
> + * @returns Index of the first entry in this bin. If the bin is empty the
> + *	    function returns negative error identifier (KS_EMPTY_BIN).
> + */
> +ssize_t ksmodel_first_index_at_bin(struct kshark_trace_histo *histo, int bin)
> +{
> +	if (bin >= 0 && bin < (int) histo->n_bins)
> +		return histo->map[bin];
> +
> +	if (bin == UPPER_OVERFLOW_BIN)
> +		return histo->map[histo->n_bins];

		return histo->map[UOB(histo)];

> +
> +	if (bin == LOWER_OVERFLOW_BIN)
> +		return histo->map[histo->n_bins + 1];

		return histo->map[LOB(histo)];

> +
> +	return KS_EMPTY_BIN;
> +}
> +
> +/**
> + * @brief Get the index of the last entry in a given bin.
> + * @param histo: Input location for the model descriptor.
> + * @param bin: Bin id.
> + * @returns Index of the last entry in this bin. If the bin is empty the
> + *	    function returns negative error identifier (KS_EMPTY_BIN).
> + */
> +ssize_t ksmodel_last_index_at_bin(struct kshark_trace_histo *histo, int bin)
> +{
> +	ssize_t index = ksmodel_first_index_at_bin(histo, bin);
> +	size_t count = ksmodel_bin_count(histo, bin);
> +
> +	if (index >= 0 && count)
> +		index += count - 1;
> +
> +	return index;
> +}
> +
> +static bool ksmodel_is_visible(struct kshark_entry *e)
> +{
> +	if ((e->visible & KS_GRAPH_VIEW_FILTER_MASK) &&
> +	    (e->visible & KS_EVENT_VIEW_FILTER_MASK))
> +		return true;
> +
> +	return false;
> +}
> +
> +static struct kshark_entry_request *
> +ksmodel_entry_front_request_alloc(struct kshark_trace_histo *histo,
> +				  int bin, bool vis_only,
> +				  matching_condition_func func, int val)
> +{
> +	struct kshark_entry_request *req;
> +	size_t first, n;
> +
> +	/* Get the number of entries in this bin. */
> +	n = ksmodel_bin_count(histo, bin);
> +	if (!n)
> +		return NULL;
> +
> +	first = ksmodel_first_index_at_bin(histo, bin);
> +
> +	req = kshark_entry_request_alloc(first, n,
> +					 func, val,
> +					 vis_only, KS_GRAPH_VIEW_FILTER_MASK);

No need for req; just return the function:

	return kshark_entry_request_alloc(...);

> +
> +	return req;
> +}
> +
> +static struct kshark_entry_request *
> +ksmodel_entry_back_request_alloc(struct kshark_trace_histo *histo,
> +				 int bin, bool vis_only,
> +				 matching_condition_func func, int val)
> +{
> +	struct kshark_entry_request *req;
> +	size_t first, n;
> +
> +	/* Get the number of entries in this bin. */
> +	n = ksmodel_bin_count(histo, bin);
> +	if (!n)
> +		return NULL;
> +
> +	first = ksmodel_last_index_at_bin(histo, bin);
> +
> +	req = kshark_entry_request_alloc(first, n,
> +					 func, val,
> +					 vis_only, KS_GRAPH_VIEW_FILTER_MASK);

Same here.

> +
> +	return req;
> +}
> +
> +/**
> + * @brief Get the index of the first entry from a given Cpu in a given bin.
> + * @param histo: Input location for the model descriptor.
> + * @param bin: Bin id.
> + * @param cpu: Cpu Id.
> + * @returns Index of the first entry from a given Cpu in this bin.
> + */
> +ssize_t ksmodel_first_index_at_cpu(struct kshark_trace_histo *histo,
> +				   int bin, int cpu)
> +{
> +	size_t i, n, first, not_found = KS_EMPTY_BIN;
> +
> +	n = ksmodel_bin_count(histo, bin);
> +	if (!n)
> +		return not_found;
> +
> +	first = ksmodel_first_index_at_bin(histo, bin);

I wonder what this is used for. Don't we have per cpu arrays or link
lists?

> +
> +	for (i = first; i < first + n; ++i) {
> +		if (histo->data[i]->cpu == cpu) {
> +			if (ksmodel_is_visible(histo->data[i]))
> +				return i;
> +			else
> +				not_found = KS_FILTERED_BIN;
> +		}
> +	}
> +
> +	return not_found;
> +}
> +
> +/**
> + * @brief Get the index of the first entry from a given Task in a given bin.
> + * @param histo: Input location for the model descriptor.
> + * @param bin: Bin id.
> + * @param pid: Process Id of a task.
> + * @returns Index of the first entry from a given Task in this bin.
> + */
> +ssize_t ksmodel_first_index_at_pid(struct kshark_trace_histo *histo,
> +				   int bin, int pid)
> +{
> +	size_t i, n, first, not_found = KS_EMPTY_BIN;
> +
> +	n = ksmodel_bin_count(histo, bin);
> +	if (!n)
> +		return not_found;
> +
> +	first = ksmodel_first_index_at_bin(histo, bin);
> +	
> +	for (i = first; i < first + n; ++i) {
> +		if (histo->data[i]->pid == pid) {
> +			if (ksmodel_is_visible(histo->data[i]))
> +				return i;
> +			else
> +				not_found = KS_FILTERED_BIN;
> +		}
> +	}
> +
> +	return not_found;
> +}
> +
> +/**
> + * @brief In a given bin, start from the front end of the bin and go towards
> + *	  the back end, searching for an entry satisfying the Matching
> + *	  condition defined by a Matching condition function.
> + * @param histo: Input location for the model descriptor.
> + * @param bin: Bin id.
> + * @param vis_only: If true, a visible entry is requested.
> + * @param func: Matching condition function.
> + * @param val: Matching condition value, used by the Matching condition
> + *	       function.
> + * @param index: Optional output location for the index of the requested
> + *		 entry inside the array.
> + * @returns Pointer ot a kshark_entry, if an entry has been found. Else NULL.
> + */
> +const struct kshark_entry *
> +ksmodel_get_entry_front(struct kshark_trace_histo *histo,
> +			int bin, bool vis_only,
> +			matching_condition_func func, int val,
> +			ssize_t *index)
> +{
> +	struct kshark_entry_request *req;
> +	const struct kshark_entry *entry;
> +
> +	if (index)
> +		*index = KS_EMPTY_BIN;
> +
> +	/* Set the position at the beginning of the bin and go forward. */
> +	req = ksmodel_entry_front_request_alloc(histo, bin, vis_only,
> +							    func, val);
> +	if (!req)
> +		return NULL;
> +
> +	entry = kshark_get_entry_front(req, histo->data, index);
> +	free(req);
> +
> +	return entry;
> +}

We could save on the allocation if we were to create the following:

void
kshark_entry_request_set(struct kshark_entry_request *req,
			 size_t first, size_t n,
			 matching_condition_func cond, int val,
			 bool vis_only, int vis_mask)
{
	req->first = first;
	req->n = n;
	req->cond = cond;
	req->val = val;
	req->vis_only = vis_only;
	req->vis_mask = vis_mask;
}

bool
ksmodel_entry_front_request_set(struct kshark_trace_histo *histo,
				struct kshark_entry_request *req,
				int bin, bool vis_only,
				matching_condition_func func, int val)
{
	size_t first, n;

	/* Get the number of entries in this bin. */
	n = ksmodel_bin_count(histo, bin);
	if (!n)
		return false;

	first = ksmodel_first_index_at_bin(histo, bin);

	kshark_entry_request_set(first, n,
			       func, val,
			       vis_only, KS_GRAPH_VIEW_FILTER_MASK);

	return true;
}

const struct kshark_entry *
ksmodel_get_entry_front(struct kshark_trace_histo *histo,
			int bin, bool vis_only,
			matching_condition_func func, int val,
			ssize_t *index)
{
	struct kshark_entry_request req;
	const struct kshark_entry *entry;
	bool ret;

	if (index)
		*index = KS_EMPTY_BIN;

	/* Set the position at the beginning of the bin and go forward. */
	ret = ksmodel_entry_front_request_set(histo, bin, vis_only,
							    func, val);
	if (!ret)
		return NULL;

	entry = kshark_get_entry_front(req, histo->data, index);

	return entry;
}

> +
> +/**
> + * @brief In a given bin, start from the back end of the bin and go towards
> + *	  the front end, searching for an entry satisfying the Matching
> + *	  condition defined by a Matching condition function.
> + * @param histo: Input location for the model descriptor.
> + * @param bin: Bin id.
> + * @param vis_only: If true, a visible entry is requested.
> + * @param func: Matching condition function.
> + * @param val: Matching condition value, used by the Matching condition
> + *	       function.
> + * @param index: Optional output location for the index of the requested
> + *		 entry inside the array.
> + * @returns Pointer ot a kshark_entry, if an entry has been found. Else NULL.
> + */
> +const struct kshark_entry *
> +ksmodel_get_entry_back(struct kshark_trace_histo *histo,
> +		       int bin, bool vis_only,
> +		       matching_condition_func func, int val,
> +		       ssize_t *index)
> +{
> +	struct kshark_entry_request *req;
> +	const struct kshark_entry *entry;
> +
> +	if (index)
> +		*index = KS_EMPTY_BIN;
> +
> +	/* Set the position at the end of the bin and go backwards. */
> +	req = ksmodel_entry_back_request_alloc(histo, bin, vis_only,
> +							   func, val);
> +	if (!req)
> +		return NULL;
> +
> +	entry = kshark_get_entry_back(req, histo->data, index);
> +	free(req);

Ditto.


> +
> +	return entry;
> +}
> +
> +static int ksmodel_get_entry_pid(const struct kshark_entry *entry)
> +{
> +	if (!entry) {
> +		/* No data has been found. */
> +		return KS_EMPTY_BIN;
> +	}
> +
> +	/*
> +	 * Note that if some data has been found, but this data is
> +	 * filtered-outa, the Dummy entry is returned. The PID of the Dummy
> +	 * entry is KS_FILTERED_BIN.
> +	 */
> +
> +	return entry->pid;
> +}
> +
> +/**
> + * @brief In a given bin, start from the front end of the bin and go towards
> + *	  the back end, searching for an entry from a given CPU. Return
> + *	  the Process Id of the task of the entry found.
> + * @param histo: Input location for the model descriptor.
> + * @param bin: Bin id.
> + * @param cpu: CPU Id.
> + * @param vis_only: If true, a visible entry is requested.
> + * @param index: Optional output location for the index of the requested
> + *		 entry inside the array.
> + * @returns Process Id of the task if an entry has been found. Else a negative
> + *	    Identifier (KS_EMPTY_BIN or KS_FILTERED_BIN).
> + */
> +int ksmodel_get_pid_front(struct kshark_trace_histo *histo,
> +			  int bin, int cpu, bool vis_only,
> +			  ssize_t *index)
> +{
> +	const struct kshark_entry *entry;
> +
> +	if (cpu < 0)
> +		return KS_EMPTY_BIN;
> +
> +	entry = ksmodel_get_entry_front(histo, bin, vis_only,
> +					       kshark_match_cpu, cpu,
> +					       index);
> +	return ksmodel_get_entry_pid(entry);
> +}
> +
> +/**
> + * @brief In a given bin, start from the back end of the bin and go towards
> + *	  the front end, searching for an entry from a given CPU. Return
> + *	  the Process Id of the task of the entry found.
> + * @param histo: Input location for the model descriptor.
> + * @param bin: Bin id.
> + * @param cpu: CPU Id.
> + * @param vis_only: If true, a visible entry is requested.
> + * @param index: Optional output location for the index of the requested
> + *		 entry inside the array.
> + * @returns Process Id of the task if an entry has been found. Else a negative
> + *	    Identifier (KS_EMPTY_BIN or KS_FILTERED_BIN).
> + */
> +int ksmodel_get_pid_back(struct kshark_trace_histo *histo,
> +			 int bin, int cpu, bool vis_only,
> +			 ssize_t *index)
> +{
> +	const struct kshark_entry *entry;
> +
> +	if (cpu < 0)
> +		return KS_EMPTY_BIN;
> +
> +	entry = ksmodel_get_entry_back(histo, bin, vis_only,
> +					      kshark_match_cpu, cpu,
> +					      index);
> +
> +	return ksmodel_get_entry_pid(entry);
> +}
> +
> +static int ksmodel_get_entry_cpu(const struct kshark_entry *entry)
> +{
> +	if (!entry) {
> +		/* No data has been found. */
> +		return KS_EMPTY_BIN;
> +	}
> +
> +	/*
> +	 * Note that if some data has been found, but this data is
> +	 * filtered-outa, the Dummy entry is returned. The CPU Id of the Dummy
> +	 * entry is KS_FILTERED_BIN.
> +	 */
> +
> +	return entry->cpu;
> +}
> +
> +/**
> + * @brief In a given bin, start from the front end of the bin and go towards
> + *	  the back end, searching for an entry from a given PID. Return
> + *	  the CPU Id of the entry found.
> + * @param histo: Input location for the model descriptor.
> + * @param bin: Bin id.
> + * @param pid: Process Id.
> + * @param vis_only: If true, a visible entry is requested.
> + * @param index: Optional output location for the index of the requested
> + *		 entry inside the array.
> + * @returns Process Id of the task if an entry has been found. Else a negative
> + *	    Identifier (KS_EMPTY_BIN or KS_FILTERED_BIN).
> + */
> +int ksmodel_get_cpu_front(struct kshark_trace_histo *histo,
> +			  int bin, int pid, bool vis_only,
> +			  ssize_t *index)
> +{
> +	const struct kshark_entry *entry;
> +
> +	if (pid < 0)
> +		return KS_EMPTY_BIN;
> +
> +	entry = ksmodel_get_entry_front(histo, bin, vis_only,
> +					       kshark_match_pid, pid,
> +					       index);
> +	return ksmodel_get_entry_cpu(entry);
> +}
> +
> +/**
> + * @brief In a given bin, start from the back end of the bin and go towards
> + *	  the front end, searching for an entry from a given PID. Return
> + *	  the CPU Id of the entry found.
> + * @param histo: Input location for the model descriptor.
> + * @param bin: Bin id.
> + * @param pid: Process Id.
> + * @param vis_only: If true, a visible entry is requested.
> + * @param index: Optional output location for the index of the requested
> + *		 entry inside the array.
> + * @returns Process Id of the task if an entry has been found. Else a negative
> + *	    Identifier (KS_EMPTY_BIN or KS_FILTERED_BIN).
> + */
> +int ksmodel_get_cpu_back(struct kshark_trace_histo *histo,
> +			 int bin, int pid, bool vis_only,
> +			 ssize_t *index)
> +{
> +	const struct kshark_entry *entry;
> +
> +	if (pid < 0)
> +		return KS_EMPTY_BIN;
> +
> +	entry = ksmodel_get_entry_back(histo, bin, vis_only,
> +					      kshark_match_pid, pid,
> +					      index);
> +
> +	return ksmodel_get_entry_cpu(entry);
> +}
> +
> +/**
> + * @brief Check if a visible trace event from a given Cpu exists in this bin.
> + * @param histo: Input location for the model descriptor.
> + * @param bin: Bin id.
> + * @param cpu: Cpu Id.
> + * @param index: Optional output location for the index of the requested
> + *		 entry inside the array.
> + * @returns True, if a visible entry exists in this bin. Else false.
> + */
> +bool ksmodel_cpu_visible_event_exist(struct kshark_trace_histo *histo,
> +				     int bin, int cpu, ssize_t *index)
> +{
> +	struct kshark_entry_request *req;
> +	const struct kshark_entry *entry;
> +
> +	if (index)
> +		*index = KS_EMPTY_BIN;
> +
> +	/* Set the position at the beginning of the bin and go forward. */
> +	req = ksmodel_entry_front_request_alloc(histo,
> +						bin, true,
> +						kshark_match_cpu, cpu);

And would save an allocation here too.

> +	if (!req)
> +		return false;
> +
> +	/*
> +	 * The default visibility mask of the Model Data request is
> +	 * KS_GRAPH_VIEW_FILTER_MASK. Change the mask to
> +	 * KS_EVENT_VIEW_FILTER_MASK because we want to find a visible event.
> +	 */
> +	req->vis_mask = KS_EVENT_VIEW_FILTER_MASK;
> +
> +	entry = kshark_get_entry_front(req, histo->data, index);
> +	free(req);
> +
> +	if (!entry || !entry->visible) {
> +		/* No visible entry has been found. */
> +		return false;
> +	}
> +
> +	return true;
> +}
> +
> +/**
> + * @brief Check if a visible trace event from a given Task exists in this bin.
> + * @param histo: Input location for the model descriptor.
> + * @param bin: Bin id.
> + * @param pid: Process Id of the task.
> + * @param index: Optional output location for the index of the requested
> + *		 entry inside the array.
> + * @returns True, if a visible entry exists in this bin. Else false.
> + */
> +bool ksmodel_task_visible_event_exist(struct kshark_trace_histo *histo,
> +				      int bin, int pid, ssize_t *index)
> +{
> +	struct kshark_entry_request *req;
> +	const struct kshark_entry *entry;
> +
> +	if (index)
> +		*index = KS_EMPTY_BIN;
> +
> +	/* Set the position at the beginning of the bin and go forward. */
> +	req = ksmodel_entry_front_request_alloc(histo,
> +						bin, true,
> +						kshark_match_pid, pid);
> +	if (!req)
> +		return false;
> +
> +	/*
> +	 * The default visibility mask of the Model Data request is
> +	 * KS_GRAPH_VIEW_FILTER_MASK. Change the mask to
> +	 * KS_EVENT_VIEW_FILTER_MASK because we want to find a visible event.
> +	 */
> +	req->vis_mask = KS_EVENT_VIEW_FILTER_MASK;
> +
> +	entry = kshark_get_entry_front(req, histo->data, index);
> +	free(req);

And here.

-- Steve

> +
> +	if (!entry || !entry->visible) {
> +		/* No visible entry has been found. */
> +		return false;
> +	}
> +
> +	return true;
> +}

Steven Rostedt Aug. 1, 2018, 6:50 p.m. UTC | #6

On Tue, 31 Jul 2018 16:52:44 +0300
"Yordan Karadzhov (VMware)" <[e-mail]> wrote:

> index 0000000..15391a9
> --- /dev/null
> +++ b/kernel-shark-qt/src/libkshark-model.h
> @@ -0,0 +1,142 @@
> +/* SPDX-License-Identifier: LGPL-2.1 */
> +
> +/*
> + * Copyright (C) 2017 VMware Inc, Yordan Karadzhov <[e-mail]>
> + */
> +
> + /**
> +  *  @file    libkshark-model.h
> +  *  @brief   Visualization model for FTRACE (trace-cmd) data.
> +  */
> +
> +#ifndef _LIB_KSHARK_MODEL_H
> +#define _LIB_KSHARK_MODEL_H
> +
> +// KernelShark
> +#include "libkshark.h"
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif // __cplusplus
> +
> +/** Overflow Bin identifiers. */

Should add what an "Overflow Bin" is.

> +enum OverflowBin {
> +	/** Identifier of the Upper Overflow Bin. */
> +	UPPER_OVERFLOW_BIN = -1,
> +
> +	/** Identifier of the Lower Overflow Bin. */
> +	LOWER_OVERFLOW_BIN = -2,
> +};
> +
> +/** Structure describing the current state of the visualization model. */
> +struct kshark_trace_histo {
> +	/** Trace data. */
> +	struct kshark_entry	**data;
> +
> +	/** The size of the data. */

	/** The size of the above data array */

> +	size_t			data_size;
> +
> +	/** The index of the first entry in each bin. */

	/** The first entry (index of data array) in each bin */

> +	ssize_t			*map;
> +
> +	/** Number of entries in each bin. */
> +	size_t			*bin_count;
> +
> +	/** Lower edge of the time-window to be visualized. */
> +	uint64_t		min;
> +
> +	/** Upper edge of the time-window to be visualized. */
> +	uint64_t		max;
> +
> +	/** The size of the bins. */

	/** The size in time for each bin */

> +	uint64_t		bin_size;
> +
> +	/** Number of bins. */
> +	int			n_bins;
> +};

The rest looks good. Ug that was a big patch to review! ;-)

-- Steve

> +
> +void ksmodel_init(struct kshark_trace_histo *histo);
> +
> +void ksmodel_clear(struct kshark_trace_histo *histo);
> +
> +void ksmodel_set_bining(struct kshark_trace_histo *histo,
> +			size_t n, uint64_t min, uint64_t max);
> +
> +void ksmodel_fill(struct kshark_trace_histo *histo,
> +		  struct kshark_entry **data, size_t n);
> +
> +size_t ksmodel_bin_count(struct kshark_trace_histo *histo, int bin);
> +
> +void ksmodel_shift_forward(struct kshark_trace_histo *histo, size_t n);
> +
> +void ksmodel_shift_backward(struct kshark_trace_histo *histo, size_t n);
> +
> +void ksmodel_jump_to(struct kshark_trace_histo *histo, size_t ts);
> +
> +void ksmodel_zoom_out(struct kshark_trace_histo *histo,
> +		      double r, int mark);
> +
> +void ksmodel_zoom_in(struct kshark_trace_histo *histo,
> +		     double r, int mark);
> +
> +ssize_t ksmodel_first_index_at_bin(struct kshark_trace_histo *histo, int bin);
> +
> +ssize_t ksmodel_last_index_at_bin(struct kshark_trace_histo *histo, int bin);
> +
> +ssize_t ksmodel_first_index_at_cpu(struct kshark_trace_histo *histo,
> +				   int bin, int cpu);
> +
> +ssize_t ksmodel_first_index_at_pid(struct kshark_trace_histo *histo,
> +				   int bin, int pid);
> +
> +const struct kshark_entry *
> +ksmodel_get_entry_front(struct kshark_trace_histo *histo,
> +			int bin, bool vis_only,
> +			matching_condition_func func, int val,
> +			ssize_t *index);
> +
> +const struct kshark_entry *
> +ksmodel_get_entry_back(struct kshark_trace_histo *histo,
> +		       int bin, bool vis_only,
> +		       matching_condition_func func, int val,
> +		       ssize_t *index);
> +
> +int ksmodel_get_pid_front(struct kshark_trace_histo *histo,
> +			  int bin, int cpu, bool vis_only,
> +			  ssize_t *index);
> +
> +int ksmodel_get_pid_back(struct kshark_trace_histo *histo,
> +			 int bin, int cpu, bool vis_only,
> +			 ssize_t *index);
> +
> +int ksmodel_get_cpu_front(struct kshark_trace_histo *histo,
> +			  int bin, int pid, bool vis_only,
> +			  ssize_t *index);
> +
> +int ksmodel_get_cpu_back(struct kshark_trace_histo *histo,
> +			 int bin, int pid, bool vis_only,
> +			 ssize_t *index);
> +
> +bool ksmodel_cpu_visible_event_exist(struct kshark_trace_histo *histo,
> +				     int bin, int cpu, ssize_t *index);
> +
> +bool ksmodel_task_visible_event_exist(struct kshark_trace_histo *histo,
> +				      int bin, int pid, ssize_t *index);
> +
> +static inline double ksmodel_bin_time(struct kshark_trace_histo *histo,
> +				      int bin)
> +{
> +	return (histo->min + bin*histo->bin_size) * 1e-9;
> +}
> +
> +static inline uint64_t ksmodel_bin_ts(struct kshark_trace_histo *histo,
> +				      int bin)
> +{
> +	return (histo->min + bin*histo->bin_size);
> +}
> +
> +#ifdef __cplusplus
> +}
> +#endif // __cplusplus
> +
> +#endif

Yordan Karadzhov Aug. 1, 2018, 7:06 p.m. UTC | #7

On 1.08.2018 21:50, Steven Rostedt wrote:
>> +};
> The rest looks good. Ug that was a big patch to review!;-)
It was a big patch indeed. Thank you very much!!!
Please hold on the review of [4/7], because I found couple of bugs in 
this patch. I will send v3 tomorrow.

Yordan

>
> -- Steve
>

Steven Rostedt Aug. 1, 2018, 7:11 p.m. UTC | #8

On Wed, 1 Aug 2018 22:06:44 +0300
Yordan Karadzhov <[e-mail]> wrote:

> On 1.08.2018 21:50, Steven Rostedt wrote:
> >> +};  
> > The rest looks good. Ug that was a big patch to review!;-)  
> It was a big patch indeed. Thank you very much!!!
> Please hold on the review of [4/7], because I found couple of bugs in 
> this patch. I will send v3 tomorrow.
> 

Thanks for letting me know!

-- Steve

Yordan Karadzhov Aug. 2, 2018, 12:59 p.m. UTC | #9

On  1.08.2018 21:22, Steven Rostedt wrote:
>> +	/*
>> +	 * Calculate the new range of the histo. Use the bin of the marker
>> +	 * as a focal point for the zoomout. With this the maker will stay
>> +	 * inside the same bin in the new histo.
>> +	 */
>> +	range = histo->max - histo->min;
>> +	delta_tot = range * r;
>> +	delta_min = delta_tot * mark / histo->n_bins;
>> +
>> +	min = histo->min - delta_min;
>> +	max = histo->max + (size_t) delta_tot - delta_min;
> Took me a bit to figure out what exactly the above is doing. Let me
> explain what I think it is doing and you can correct me if I'm wrong.
> 
> We set delta_tot to increase by the percentage requested (easy).
> 
> Now we make delta_min equal to a percentage of delta_tot based on where
> mark is in the original bins. If mark is zero, then mark was at 0% of
> the original bins, if it was at histo->n_bins - 1, it was at (almost)
> 100%. If it is half way, then we place delta_min at %50 of delta_tot.
> 
> Then we subtract the original min by the delta_tot * mark/n_bins
> percentage, and add the max by delta_tot * (1 - mark/n_bins).
> 
> Sound right? Maybe we can add a comment saying such?
> 

Yes, this is a correct explanation. I will use it as a comment in the code.

Thanks!
Yordan

Yordan Karadzhov Aug. 3, 2018, 2:01 p.m. UTC | #10

On  1.08.2018 21:44, Steven Rostedt wrote:
>> +
>> +/**
>> + * @brief In a given bin, start from the front end of the bin and go towards
>> + *	  the back end, searching for an entry satisfying the Matching
>> + *	  condition defined by a Matching condition function.
>> + * @param histo: Input location for the model descriptor.
>> + * @param bin: Bin id.
>> + * @param vis_only: If true, a visible entry is requested.
>> + * @param func: Matching condition function.
>> + * @param val: Matching condition value, used by the Matching condition
>> + *	       function.
>> + * @param index: Optional output location for the index of the requested
>> + *		 entry inside the array.
>> + * @returns Pointer ot a kshark_entry, if an entry has been found. Else NULL.
>> + */
>> +const struct kshark_entry *
>> +ksmodel_get_entry_front(struct kshark_trace_histo *histo,
>> +			int bin, bool vis_only,
>> +			matching_condition_func func, int val,
>> +			ssize_t *index)
>> +{
>> +	struct kshark_entry_request *req;
>> +	const struct kshark_entry *entry;
>> +
>> +	if (index)
>> +		*index = KS_EMPTY_BIN;
>> +
>> +	/* Set the position at the beginning of the bin and go forward. */
>> +	req = ksmodel_entry_front_request_alloc(histo, bin, vis_only,
>> +							    func, val);
>> +	if (!req)
>> +		return NULL;
>> +
>> +	entry = kshark_get_entry_front(req, histo->data, index);
>> +	free(req);
>> +
>> +	return entry;
>> +}
> We could save on the allocation if we were to create the following:
> 
> void
> kshark_entry_request_set(struct kshark_entry_request *req,
> 			 size_t first, size_t n,
> 			 matching_condition_func cond, int val,
> 			 bool vis_only, int vis_mask)
> {
> 	req->first = first;
> 	req->n = n;
> 	req->cond = cond;
> 	req->val = val;
> 	req->vis_only = vis_only;
> 	req->vis_mask = vis_mask;
> }
> 
> bool
> ksmodel_entry_front_request_set(struct kshark_trace_histo *histo,
> 				struct kshark_entry_request *req,
> 				int bin, bool vis_only,
> 				matching_condition_func func, int val)
> {
> 	size_t first, n;
> 
> 	/* Get the number of entries in this bin. */
> 	n = ksmodel_bin_count(histo, bin);
> 	if (!n)
> 		return false;
> 
> 	first = ksmodel_first_index_at_bin(histo, bin);
> 
> 	kshark_entry_request_set(first, n,
> 			       func, val,
> 			       vis_only, KS_GRAPH_VIEW_FILTER_MASK);
> 
> 	return true;
> }
> 
> const struct kshark_entry *
> ksmodel_get_entry_front(struct kshark_trace_histo *histo,
> 			int bin, bool vis_only,
> 			matching_condition_func func, int val,
> 			ssize_t *index)
> {
> 	struct kshark_entry_request req;
> 	const struct kshark_entry *entry;
> 	bool ret;
> 
> 	if (index)
> 		*index = KS_EMPTY_BIN;
> 
> 	/* Set the position at the beginning of the bin and go forward. */
> 	ret = ksmodel_entry_front_request_set(histo, bin, vis_only,
> 							    func, val);
> 	if (!ret)
> 		return NULL;
> 
> 	entry = kshark_get_entry_front(req, histo->data, index);
> 
> 	return entry;
> }
> 

Hi Steven,
I have tried implementing this, but it becomes a bit ugly in the 
following patches where the single request is transformed into a linked 
list of requests.

Thanks!
Yordan

Steven Rostedt Aug. 3, 2018, 4 p.m. UTC | #11

On Fri, 3 Aug 2018 17:01:45 +0300
"Yordan Karadzhov (VMware)" <[e-mail]> wrote:

> Hi Steven,
> I have tried implementing this, but it becomes a bit ugly in the 
> following patches where the single request is transformed into a linked 
> list of requests.

OK. Then let's not implement it, and see if we can clean it up later
after most of the changes have been made. I was hoping that it would
make the later patches better, but if that's not the case, then let's
ditch the idea.

-- Steve

Steven Rostedt Aug. 3, 2018, 6:48 p.m. UTC | #12

On Tue, 31 Jul 2018 20:51:13 -0400
Steven Rostedt <[e-mail]> wrote:

> > +static void ksmodel_reset_bins(struct kshark_trace_histo *histo,
> > +			       size_t first, size_t last)
> > +{
> > +	/* Reset the content of the bins. */
> > +	memset(&histo->map[first], KS_EMPTY_BIN,
> > +	       (last - first + 1) * sizeof(histo->map[0]));  
> 
> This patch should add a comment here and by KS_EMPTY_BIN stating that
> KS_EMPTY_BIN is expected to be -1, as it is used to reset the entire
> array with memset(). As memset() only updates an array to a single
> byte, that byte must be the same throughout. Which works for zero and
> -1.
> 

Note, I added this too.

-- Steve

diff --git a/kernel-shark-qt/src/libkshark.h b/kernel-shark-qt/src/libkshark.h
index 4860e74d..122c030e 100644
--- a/kernel-shark-qt/src/libkshark.h
+++ b/kernel-shark-qt/src/libkshark.h
@@ -225,7 +225,10 @@ bool kshark_match_pid(struct kshark_context *kshark_ctx,
 bool kshark_match_cpu(struct kshark_context *kshark_ctx,
 		      struct kshark_entry *e, int cpu);
 
-/** Empty bin identifier. */
+/** Empty bin identifier.
+ * KS_EMPTY_BIN is used to reset entire arrays to empty with memset(),
+ * thus it must be -1 for that to work.
+ */
 #define KS_EMPTY_BIN		-1
 
 /** Filtered bin identifier. */

Patch

diff --git a/kernel-shark-qt/src/CMakeLists.txt b/kernel-shark-qt/src/CMakeLists.txt
index ed3c60e..ec22f63 100644
--- a/kernel-shark-qt/src/CMakeLists.txt
+++ b/kernel-shark-qt/src/CMakeLists.txt
@@ -1,7 +1,8 @@ 
 message("\n src ...")
 
 message(STATUS "libkshark")
-add_library(kshark SHARED libkshark.c)
+add_library(kshark SHARED libkshark.c
+                          libkshark-model.c)
 
 target_link_libraries(kshark ${CMAKE_DL_LIBS}
                              ${TRACEEVENT_LIBRARY}
diff --git a/kernel-shark-qt/src/libkshark-model.c b/kernel-shark-qt/src/libkshark-model.c
new file mode 100644
index 0000000..4a4e910
--- /dev/null
+++ b/kernel-shark-qt/src/libkshark-model.c
@@ -0,0 +1,1135 @@ 
+// SPDX-License-Identifier: LGPL-2.1
+
+/*
+ * Copyright (C) 2017 VMware Inc, Yordan Karadzhov <[e-mail]>
+ */
+
+ /**
+  *  @file    libkshark.c
+  *  @brief   Visualization model for FTRACE (trace-cmd) data.
+  */
+
+// C
+#include <stdlib.h>
+
+// KernelShark
+#include "libkshark-model.h"
+
+#define UOB(histo) (histo->n_bins)
+#define LOB(histo) (histo->n_bins + 1)
+
+/**
+ * @brief Initialize the Visualization model.
+ * @param histo: Input location for the model descriptor.
+ */
+void ksmodel_init(struct kshark_trace_histo *histo)
+{
+	/*
+	 * Initialize an empty histo. The histo will have no bins and will
+	 * contain no data.
+	 */
+	histo->bin_size = 0;
+	histo->min = 0;
+	histo->max = 0;
+	histo->n_bins = 0;
+
+	histo->bin_count = NULL;
+	histo->map = NULL;
+}
+
+/**
+ * @brief Clear (reset) the Visualization model.
+ * @param histo: Input location for the model descriptor.
+ */
+void ksmodel_clear(struct kshark_trace_histo *histo)
+{
+	/* Reset the histo. It will have no bins and will contain no data. */
+	free(histo->map);
+	free(histo->bin_count);
+	ksmodel_init(histo);
+}
+
+static void ksmodel_reset_bins(struct kshark_trace_histo *histo,
+			       size_t first, size_t last)
+{
+	/* Reset the content of the bins. */
+	memset(&histo->map[first], KS_EMPTY_BIN,
+	       (last - first + 1) * sizeof(histo->map[0]));
+
+	memset(&histo->bin_count[first], 0,
+	       (last - first + 1) * sizeof(histo->bin_count[0]));
+}
+
+static bool ksmodel_histo_alloc(struct kshark_trace_histo *histo, size_t n)
+{
+	free(histo->bin_count);
+	free(histo->map);
+
+	/* Create bins. Two overflow bins are added. */
+	histo->map = calloc(n + 2, sizeof(*histo->map));
+	histo->bin_count = calloc(n + 2, sizeof(*histo->bin_count));
+
+	if (!histo->map || !histo->bin_count) {
+		ksmodel_clear(histo);
+		fprintf(stderr, "Failed to allocate memory for a histo.\n");
+		return false;
+	}
+
+	histo->n_bins = n;
+
+	return true;
+}
+
+static void ksmodel_set_in_range_bining(struct kshark_trace_histo *histo,
+					size_t n, uint64_t min, uint64_t max,
+					bool force_in_range)
+{
+	uint64_t corrected_range, delta_range, range = max - min;
+	struct kshark_entry *last;
+
+	/* The size of the bin must be >= 1, hence the range must be >= n. */
+	if (n == 0 || range < n)
+		return;
+
+	/*
+	 * If the number of bins changes, allocate memory for the descriptor
+	 * of the model.
+	 */
+	if (n != histo->n_bins) {
+		if (!ksmodel_histo_alloc(histo, n)) {
+			ksmodel_clear(histo);
+			return;
+		}
+	}
+
+	/* Reset the content of all bins (including overflow bins) to zero. */
+	ksmodel_reset_bins(histo, 0, histo->n_bins + 1);
+
+	if (range % n == 0) {
+		/*
+		 * The range is multiple of the number of bin and needs no
+		 * adjustment. This is very unlikely to happen but still ...
+		 */
+		histo->min = min;
+		histo->max = max;
+		histo->bin_size = range / n;
+	} else {
+		/*
+		 * The range needs adjustment. The new range will be slightly
+		 * bigger, compared to the requested one.
+		 */
+		histo->bin_size = range / n + 1;
+		corrected_range = histo->bin_size * n;
+		delta_range = corrected_range - range;
+		histo->min = min - delta_range / 2;
+		histo->max = histo->min + corrected_range;
+
+		if (!force_in_range)
+			return;
+
+		/*
+		 * Make sure that the new range doesn't go outside of the time
+		 * interval of the dataset.
+		 */
+		last = histo->data[histo->data_size - 1];
+		if (histo->min < histo->data[0]->ts) {
+			histo->min = histo->data[0]->ts;
+			histo->max = histo->min + corrected_range;
+		} else if (histo->max > last->ts) {
+			histo->max = last->ts;
+			histo->min = histo->max - corrected_range;
+		}
+	}
+}
+
+/**
+ * @brief Prepare the bining of the Visualization model.
+ * @param histo: Input location for the model descriptor.
+ * @param n: Number of bins.
+ * @param min: Lower edge of the time-window to be visualized.
+ * @param max: Upper edge of the time-window to be visualized.
+ */
+void ksmodel_set_bining(struct kshark_trace_histo *histo,
+			size_t n, uint64_t min, uint64_t max)
+{
+	ksmodel_set_in_range_bining(histo, n, min, max, false);
+}
+
+static size_t ksmodel_set_lower_edge(struct kshark_trace_histo *histo)
+{
+	/*
+	 * Find the index of the first entry inside
+	 * the range (timestamp > min).
+	 */
+	size_t row = kshark_find_entry_by_time(histo->min,
+					       histo->data,
+					       0,
+					       histo->data_size - 1);
+
+	if (row != 0) {
+		/*
+		 * The first entry inside the range is not the first entry
+		 * of the dataset. This means that the Lower Overflow bin
+		 * contains data.
+		 */
+
+		/* Lower Overflow bin starts at "0". */
+		histo->map[LOB(histo)] = 0;
+
+		/*
+		 * The number of entries inside the Lower Overflow bin is
+		 * equal to the index of the first entry inside the range.
+		 */
+		histo->bin_count[LOB(histo)] = row;
+	}  else {
+		/* Lower Overflow bin is empty. */
+		histo->map[LOB(histo)] = KS_EMPTY_BIN;
+		histo->bin_count[LOB(histo)] = 0;
+	}
+
+	/*
+	 * Now check if the first entry inside the range falls into the
+	 * first bin.
+	 */
+	if (histo->data[row]->ts  < histo->min + histo->bin_size) {
+		/*
+		 * It is inside the first bin. Set the beginning
+		 * of the first bin.
+		 */
+		histo->map[0] = row;
+	} else {
+		/* The first bin is empty. */
+		histo->map[0] = KS_EMPTY_BIN;
+	}
+
+	return row;
+}
+
+static size_t ksmodel_set_upper_edge(struct kshark_trace_histo *histo)
+{
+	/*
+	 * Find the index of the first entry outside
+	 * the range (timestamp > max).
+	 */
+	size_t row = kshark_find_entry_by_time(histo->max,
+					       histo->data,
+					       0,
+					       histo->data_size - 1);
+
+	if (row < histo->data_size - 1 ||
+	    (row == histo->data_size - 1 &&
+	     histo->data[histo->data_size - 1]->ts > histo->max)) {
+		/*
+		 * The Upper Overflow bin contains data. Set its beginning
+		 * and the number of entries.
+		 */
+		histo->map[UOB(histo)] = row;
+		histo->bin_count[UOB(histo)] = histo->data_size - row;
+	}  else {
+		/* Upper Overflow bin is empty. */
+		histo->map[UOB(histo)] = KS_EMPTY_BIN;
+		histo->bin_count[UOB(histo)] = 0;
+	}
+
+	return row;
+}
+
+static void ksmodel_set_next_bin_edge(struct kshark_trace_histo *histo,
+				      size_t bin)
+{
+	size_t time, row, next_bin = bin + 1;
+
+	/* Calculate the beginning of the next bin. */
+	time = histo->min + next_bin * histo->bin_size;
+
+	/*
+	 * Find the index of the first entry inside
+	 * the next bin (timestamp > time).
+	 */
+	row = kshark_find_entry_by_time(time, histo->data, 0,
+					histo->data_size - 1);
+
+	/*
+	 * The timestamp of the very last entry of the dataset can be exactly
+	 * equal to the value of the upper edge of the range. This is very
+	 * likely to happen when we use ksmodel_set_in_range_bining(). In this
+	 * case we have to increase the size of the very last bin in order to
+	 * make sure that the last entry of the dataset will fall into it.
+	 */
+	if (next_bin == histo->n_bins - 1)
+		++time;
+
+	if (histo->data[row]->ts >= time + histo->bin_size) {
+		/* The bin is empty. */
+		histo->map[next_bin] = KS_EMPTY_BIN;
+		return;
+	}
+
+	/* Set the index of the first entry. */
+	histo->map[next_bin] = row;
+}
+
+static void ksmodel_set_bin_counts(struct kshark_trace_histo *histo)
+{
+	int i = 0, prev_not_empty;
+
+	memset(&histo->bin_count[0], 0,
+	       (histo->n_bins) * sizeof(histo->bin_count[0]));
+	/*
+	 * Find the first bin which contains data. Start by checking the
+	 * Lower Overflow bin.
+	 */
+	if (histo->map[histo->n_bins + 1] != KS_EMPTY_BIN) {
+		prev_not_empty = LOB(histo);
+	} else {
+		while (histo->map[i] < 0) {
+			++i;
+		}
+
+		prev_not_empty = i++;
+	}
+
+	/*
+	 * Starting from the first not empty bin, loop over all bins and fill
+	 * in the bin_count array to hold the number of entries in each bin.
+	 */
+	while (i < histo->n_bins) {
+		if (histo->map[i] != KS_EMPTY_BIN) {
+			/*
+			 * Here we set the number of entries in
+			 * "prev_not_empty" bin.
+			 */
+			histo->bin_count[prev_not_empty] =
+				histo->map[i] - histo->map[prev_not_empty];
+	
+			prev_not_empty = i;
+		}
+
+		++i;
+	}
+
+	/* Check if the Upper Overflow bin contains data. */
+	if (histo->map[UOB(histo)] == KS_EMPTY_BIN) {
+		/*
+		 * The Upper Overflow bin is empty. Use the size of the
+		 * dataset to calculate the content of the previouse not
+		 * empty bin.
+		 */
+		histo->bin_count[prev_not_empty] = histo->data_size -
+						   histo->map[prev_not_empty];
+	} else {
+		/*
+		 * Use the index of the first entry inside the Upper Overflow
+		 * bin to calculate the content of the previouse not empty
+		 * bin.
+		 */
+		histo->bin_count[prev_not_empty] = histo->map[UOB(histo)] -
+						   histo->map[prev_not_empty];
+	}
+}
+
+/**
+ * @brief Provide the Visualization model with data. Calculate the current
+ *	  state of the model.
+ * @param histo: Input location for the model descriptor.
+ * @param data: Input location for the trace data.
+ * @param n: Number of bins.
+ */
+void ksmodel_fill(struct kshark_trace_histo *histo,
+		  struct kshark_entry **data, size_t n)
+{
+	int bin;
+
+	histo->data_size = n;
+	histo->data = data;
+
+	if (histo->n_bins == 0 ||
+	    histo->bin_size == 0 ||
+	    histo->data_size == 0) {
+		/*
+		 * Something is wrong with this histo.
+		 * Most likely the binning is not set.
+		 */
+		ksmodel_clear(histo);
+		fprintf(stderr,
+			"Unable to fill the model with data.\n");
+		fprintf(stderr,
+			"Try to set the bining of the model first.\n");
+
+		return;
+	}
+
+	/* Set the Lower Overflow bin */
+	ksmodel_set_lower_edge(histo);
+
+	/*
+	 * Loop over the dataset and set the beginning of all individual bins.
+	 */
+	bin = 0;
+	for (bin = 0; bin < histo->n_bins; ++bin)
+		ksmodel_set_next_bin_edge(histo, bin);
+
+	/* Set the Upper Overflow bin. */
+	ksmodel_set_upper_edge(histo);
+
+	/* Calculate the number of entries in each bin. */
+	ksmodel_set_bin_counts(histo);
+}
+
+/**
+ * @brief Get the total number of entries in a given bin.
+ * @param histo: Input location for the model descriptor.
+ * @param bin: Bin id.
+ * @returns The number of entries in this bin.
+ */
+size_t ksmodel_bin_count(struct kshark_trace_histo *histo, int bin)
+{
+	if (bin >= 0 && bin < histo->n_bins)
+		return histo->bin_count[bin];
+
+	if (bin == UPPER_OVERFLOW_BIN)
+		return histo->bin_count[UOB(histo)];
+
+	if (bin == LOWER_OVERFLOW_BIN)
+		return histo->bin_count[LOB(histo)];
+
+	return 0;
+}
+
+/**
+ * @brief Shift the time-window of the model forward. Recalculate the current
+ *	  state of the model.
+ * @param histo: Input location for the model descriptor.
+ * @param n: Number of bins to shift.
+ */
+void ksmodel_shift_forward(struct kshark_trace_histo *histo, size_t n)
+{
+	int bin;
+	
+	if (!histo->data_size)
+		return;
+
+	if (histo->bin_count[UOB(histo)] == 0) {
+		/*
+		 * The Upper Overflow bin is empty. This means that we are at
+		 * the upper edge of the dataset already. Do nothing in this
+		 * case.
+		 */
+		return;
+	}
+
+	histo->min += n * histo->bin_size;
+	histo->max += n * histo->bin_size;
+
+	if (n >= histo->n_bins) {
+		/*
+		 * No overlap between the new and the old ranges. Recalculate
+		 * all bins from scratch. First calculate the new range.
+		 */
+		ksmodel_set_bining(histo, histo->n_bins, histo->min,
+							 histo->max);
+
+		ksmodel_fill(histo, histo->data, histo->data_size);
+		return;
+	}
+
+	/* Set the new Lower Overflow bin. */
+	ksmodel_set_lower_edge(histo);
+
+	/*
+	 * Copy the the mapping indexes of all overlaping bins starting from
+	 * bin "0" of the new histo. Note that the number of overlaping bins
+	 * is histo->n_bins - n.
+	 */
+	memmove(&histo->map[0], &histo->map[n],
+		sizeof(histo->map[0]) * (histo->n_bins - n));
+
+	/*
+	 * The the mapping index pf the old Upper Overflow bin is now index
+	 * of the first new bin.
+	 */
+	bin = UOB(histo) - n;
+	histo->map[bin] = histo->map[UOB(histo)];
+
+	/* Calculate only the content of the new (non-overlapping) bins. */
+	for (; bin < histo->n_bins; ++bin)
+		ksmodel_set_next_bin_edge(histo, bin);
+
+	/*
+	 * Set the new Upper Overflow bin and calculate the number of entries
+	 * in each bin.
+	 */
+	ksmodel_set_upper_edge(histo);
+	ksmodel_set_bin_counts(histo);
+}
+
+/**
+ * @brief Shift the time-window of the model backward. Recalculate the current
+ *	  state of the model.
+ * @param histo: Input location for the model descriptor.
+ * @param n: Number of bins to shift.
+ */
+void ksmodel_shift_backward(struct kshark_trace_histo *histo, size_t n)
+{
+	int bin;
+
+	if (!histo->data_size)
+		return;
+
+	if (histo->bin_count[LOB(histo)] == 0) {
+		/*
+		 * The Lower Overflow bin is empty. This means that we are at
+		 * the Lower edge of the dataset already. Do nothing in this
+		 * case.
+		 */
+		return;
+	}
+
+	histo->min -= n * histo->bin_size;
+	histo->max -= n * histo->bin_size;
+
+	if (n >= histo->n_bins) {
+		/*
+		 * No overlap between the new and the old range. Recalculate
+		 * all bins from scratch. First calculate the new range.
+		 */
+		ksmodel_set_bining(histo, histo->n_bins, histo->min,
+							 histo->max);
+
+		ksmodel_fill(histo, histo->data, histo->data_size);
+		return;
+	}
+
+	/*
+	 * Copy the the mapping indexes of all overlaping bins starting from
+	 * bin "0" of the old histo. Note that the number of overlaping bins
+	 * is histo->n_bins - n.
+	 */
+	memmove(&histo->map[n], &histo->map[0],
+		sizeof(histo->map[0]) * (histo->n_bins - n));
+
+	/* Set the new Lower Overflow bin. */
+	ksmodel_set_lower_edge(histo);
+
+	/* Calculate only the content of the new (non-overlapping) bins. */
+	bin = 0;
+	while (bin < n) {
+		ksmodel_set_next_bin_edge(histo, bin);
+		++bin;
+	}
+
+	/*
+	 * Set the new Upper Overflow bin and calculate the number of entries
+	 * in each bin.
+	 */
+	ksmodel_set_upper_edge(histo);
+	ksmodel_set_bin_counts(histo);
+}
+
+/**
+ * @brief Move the time-window of the model to a given location. Recalculate
+ *	  the current state of the model.
+ * @param histo: Input location for the model descriptor.
+ * @param ts: position in time to be visualized.
+ */
+void ksmodel_jump_to(struct kshark_trace_histo *histo, size_t ts)
+{
+	size_t min, max, range_min;
+
+	if (ts > histo->min && ts < histo->max) {
+		/*
+		 * The new position is already inside the range.
+		 * Do nothing in this case.
+		 */
+		return;
+	}
+
+	/*
+	 * Calculate the new range without changing the size and the number
+	 * of bins.
+	 */
+	min = ts - histo->n_bins * histo->bin_size / 2;
+
+	/* Make sure that the range does not go outside of the dataset. */
+	if (min < histo->data[0]->ts)
+		min = histo->data[0]->ts;
+
+	range_min = histo->data[histo->data_size - 1]->ts -
+		   histo->n_bins * histo->bin_size;
+
+	if (min > range_min)
+		min = range_min;
+
+	max = min + histo->n_bins * histo->bin_size;
+
+	/* Use the new range to recalculate all bins from scratch. */
+	ksmodel_set_bining(histo, histo->n_bins, min, max);
+	ksmodel_fill(histo, histo->data, histo->data_size);
+}
+
+/**
+ * @brief Extend the time-window of the model. Recalculate the current state
+ *	  of the model.
+ * @param histo: Input location for the model descriptor.
+ * @param r: Scale factor of the zoom-out.
+ * @param mark: Focus point of the zoom-out.
+ */
+void ksmodel_zoom_out(struct kshark_trace_histo *histo,
+		      double r, int mark)
+{
+	size_t range, min, max, delta_min;
+	double delta_tot;
+
+	if (!histo->data_size)
+		return;
+
+	/*
+	 * If the marker is not set, assume that the focal point of the zoom
+	 * is the center of the range.
+	 */
+	if (mark < 0)
+		mark = histo->n_bins / 2;
+
+	/*
+	 * Calculate the new range of the histo. Use the bin of the marker
+	 * as a focal point for the zoomout. With this the maker will stay
+	 * inside the same bin in the new histo.
+	 */
+	range = histo->max - histo->min;
+	delta_tot = range * r;
+	delta_min = delta_tot * mark / histo->n_bins;
+
+	min = histo->min - delta_min;
+	max = histo->max + (size_t) delta_tot - delta_min;
+
+	/* Make sure the new range doesn't go outside of the dataset. */
+	if (min < histo->data[0]->ts)
+		min = histo->data[0]->ts;
+
+	if (max > histo->data[histo->data_size - 1]->ts)
+		max = histo->data[histo->data_size - 1]->ts;
+
+	/*
+	 * Use the new range to recalculate all bins from scratch. Enforce
+	 * "In Range" adjustment of the range of the model, in order to avoid
+	 * slowly drifting outside of the data-set in the case when the very
+	 * first or the very last entry is used as a focal point.
+	 */
+	ksmodel_set_in_range_bining(histo, histo->n_bins, min, max, true);
+	ksmodel_fill(histo, histo->data, histo->data_size);
+}
+
+/**
+ * @brief Shrink the time-window of the model. Recalculate the current state
+ *	  of the model.
+ * @param histo: Input location for the model descriptor.
+ * @param r: Scale factor of the zoom-in.
+ * @param mark: Focus point of the zoom-in.
+ */
+void ksmodel_zoom_in(struct kshark_trace_histo *histo,
+		     double r, int mark)
+{
+	size_t range, min, max, delta_min;
+	double delta_tot;
+
+	if (!histo->data_size)
+		return;
+
+	/*
+	 * If the marker is not set, assume that the focal point of the zoom
+	 * is the center of the range.
+	 */
+	if (mark < 0)
+		mark = histo->n_bins / 2;
+
+	range = histo->max - histo->min;
+
+	/* Avoid overzooming. */
+	if (range < histo->n_bins * 4)
+		return;
+
+	/*
+	 * Calculate the new range of the histo. Use the bin of the marker
+	 * as a focal point for the zoomin. With this the maker will stay
+	 * inside the same bin in the new histo.
+	 */
+	delta_tot =  range * r;
+	if (mark == (int)histo->n_bins - 1)
+		delta_min = delta_tot;
+	else if (mark == 0)
+		delta_min = 0;
+	else
+		delta_min = delta_tot * mark / histo->n_bins;
+
+	min = histo->min + delta_min;
+	max = histo->max - (size_t) delta_tot + delta_min;
+
+	/*
+	 * Use the new range to recalculate all bins from scratch. Enforce
+	 * "In Range" adjustment of the range of the model, in order to avoid
+	 * slowly drifting outside of the data-set in the case when the very
+	 * first or the very last entry is used as a focal point.
+	 */
+	ksmodel_set_in_range_bining(histo, histo->n_bins, min, max, true);
+	ksmodel_fill(histo, histo->data, histo->data_size);
+}
+
+/**
+ * @brief Get the index of the first entry in a given bin.
+ * @param histo: Input location for the model descriptor.
+ * @param bin: Bin id.
+ * @returns Index of the first entry in this bin. If the bin is empty the
+ *	    function returns negative error identifier (KS_EMPTY_BIN).
+ */
+ssize_t ksmodel_first_index_at_bin(struct kshark_trace_histo *histo, int bin)
+{
+	if (bin >= 0 && bin < (int) histo->n_bins)
+		return histo->map[bin];
+
+	if (bin == UPPER_OVERFLOW_BIN)
+		return histo->map[histo->n_bins];
+
+	if (bin == LOWER_OVERFLOW_BIN)
+		return histo->map[histo->n_bins + 1];
+
+	return KS_EMPTY_BIN;
+}
+
+/**
+ * @brief Get the index of the last entry in a given bin.
+ * @param histo: Input location for the model descriptor.
+ * @param bin: Bin id.
+ * @returns Index of the last entry in this bin. If the bin is empty the
+ *	    function returns negative error identifier (KS_EMPTY_BIN).
+ */
+ssize_t ksmodel_last_index_at_bin(struct kshark_trace_histo *histo, int bin)
+{
+	ssize_t index = ksmodel_first_index_at_bin(histo, bin);
+	size_t count = ksmodel_bin_count(histo, bin);
+
+	if (index >= 0 && count)
+		index += count - 1;
+
+	return index;
+}
+
+static bool ksmodel_is_visible(struct kshark_entry *e)
+{
+	if ((e->visible & KS_GRAPH_VIEW_FILTER_MASK) &&
+	    (e->visible & KS_EVENT_VIEW_FILTER_MASK))
+		return true;
+
+	return false;
+}
+
+static struct kshark_entry_request *
+ksmodel_entry_front_request_alloc(struct kshark_trace_histo *histo,
+				  int bin, bool vis_only,
+				  matching_condition_func func, int val)
+{
+	struct kshark_entry_request *req;
+	size_t first, n;
+
+	/* Get the number of entries in this bin. */
+	n = ksmodel_bin_count(histo, bin);
+	if (!n)
+		return NULL;
+
+	first = ksmodel_first_index_at_bin(histo, bin);
+
+	req = kshark_entry_request_alloc(first, n,
+					 func, val,
+					 vis_only, KS_GRAPH_VIEW_FILTER_MASK);
+
+	return req;
+}
+
+static struct kshark_entry_request *
+ksmodel_entry_back_request_alloc(struct kshark_trace_histo *histo,
+				 int bin, bool vis_only,
+				 matching_condition_func func, int val)
+{
+	struct kshark_entry_request *req;
+	size_t first, n;
+
+	/* Get the number of entries in this bin. */
+	n = ksmodel_bin_count(histo, bin);
+	if (!n)
+		return NULL;
+
+	first = ksmodel_last_index_at_bin(histo, bin);
+
+	req = kshark_entry_request_alloc(first, n,
+					 func, val,
+					 vis_only, KS_GRAPH_VIEW_FILTER_MASK);
+
+	return req;
+}
+
+/**
+ * @brief Get the index of the first entry from a given Cpu in a given bin.
+ * @param histo: Input location for the model descriptor.
+ * @param bin: Bin id.
+ * @param cpu: Cpu Id.
+ * @returns Index of the first entry from a given Cpu in this bin.
+ */
+ssize_t ksmodel_first_index_at_cpu(struct kshark_trace_histo *histo,
+				   int bin, int cpu)
+{
+	size_t i, n, first, not_found = KS_EMPTY_BIN;
+
+	n = ksmodel_bin_count(histo, bin);
+	if (!n)
+		return not_found;
+
+	first = ksmodel_first_index_at_bin(histo, bin);
+
+	for (i = first; i < first + n; ++i) {
+		if (histo->data[i]->cpu == cpu) {
+			if (ksmodel_is_visible(histo->data[i]))
+				return i;
+			else
+				not_found = KS_FILTERED_BIN;
+		}
+	}
+
+	return not_found;
+}
+
+/**
+ * @brief Get the index of the first entry from a given Task in a given bin.
+ * @param histo: Input location for the model descriptor.
+ * @param bin: Bin id.
+ * @param pid: Process Id of a task.
+ * @returns Index of the first entry from a given Task in this bin.
+ */
+ssize_t ksmodel_first_index_at_pid(struct kshark_trace_histo *histo,
+				   int bin, int pid)
+{
+	size_t i, n, first, not_found = KS_EMPTY_BIN;
+
+	n = ksmodel_bin_count(histo, bin);
+	if (!n)
+		return not_found;
+
+	first = ksmodel_first_index_at_bin(histo, bin);
+	
+	for (i = first; i < first + n; ++i) {
+		if (histo->data[i]->pid == pid) {
+			if (ksmodel_is_visible(histo->data[i]))
+				return i;
+			else
+				not_found = KS_FILTERED_BIN;
+		}
+	}
+
+	return not_found;
+}
+
+/**
+ * @brief In a given bin, start from the front end of the bin and go towards
+ *	  the back end, searching for an entry satisfying the Matching
+ *	  condition defined by a Matching condition function.
+ * @param histo: Input location for the model descriptor.
+ * @param bin: Bin id.
+ * @param vis_only: If true, a visible entry is requested.
+ * @param func: Matching condition function.
+ * @param val: Matching condition value, used by the Matching condition
+ *	       function.
+ * @param index: Optional output location for the index of the requested
+ *		 entry inside the array.
+ * @returns Pointer ot a kshark_entry, if an entry has been found. Else NULL.
+ */
+const struct kshark_entry *
+ksmodel_get_entry_front(struct kshark_trace_histo *histo,
+			int bin, bool vis_only,
+			matching_condition_func func, int val,
+			ssize_t *index)
+{
+	struct kshark_entry_request *req;
+	const struct kshark_entry *entry;
+
+	if (index)
+		*index = KS_EMPTY_BIN;
+
+	/* Set the position at the beginning of the bin and go forward. */
+	req = ksmodel_entry_front_request_alloc(histo, bin, vis_only,
+							    func, val);
+	if (!req)
+		return NULL;
+
+	entry = kshark_get_entry_front(req, histo->data, index);
+	free(req);
+
+	return entry;
+}
+
+/**
+ * @brief In a given bin, start from the back end of the bin and go towards
+ *	  the front end, searching for an entry satisfying the Matching
+ *	  condition defined by a Matching condition function.
+ * @param histo: Input location for the model descriptor.
+ * @param bin: Bin id.
+ * @param vis_only: If true, a visible entry is requested.
+ * @param func: Matching condition function.
+ * @param val: Matching condition value, used by the Matching condition
+ *	       function.
+ * @param index: Optional output location for the index of the requested
+ *		 entry inside the array.
+ * @returns Pointer ot a kshark_entry, if an entry has been found. Else NULL.
+ */
+const struct kshark_entry *
+ksmodel_get_entry_back(struct kshark_trace_histo *histo,
+		       int bin, bool vis_only,
+		       matching_condition_func func, int val,
+		       ssize_t *index)
+{
+	struct kshark_entry_request *req;
+	const struct kshark_entry *entry;
+
+	if (index)
+		*index = KS_EMPTY_BIN;
+
+	/* Set the position at the end of the bin and go backwards. */
+	req = ksmodel_entry_back_request_alloc(histo, bin, vis_only,
+							   func, val);
+	if (!req)
+		return NULL;
+
+	entry = kshark_get_entry_back(req, histo->data, index);
+	free(req);
+
+	return entry;
+}
+
+static int ksmodel_get_entry_pid(const struct kshark_entry *entry)
+{
+	if (!entry) {
+		/* No data has been found. */
+		return KS_EMPTY_BIN;
+	}
+
+	/*
+	 * Note that if some data has been found, but this data is
+	 * filtered-outa, the Dummy entry is returned. The PID of the Dummy
+	 * entry is KS_FILTERED_BIN.
+	 */
+
+	return entry->pid;
+}
+
+/**
+ * @brief In a given bin, start from the front end of the bin and go towards
+ *	  the back end, searching for an entry from a given CPU. Return
+ *	  the Process Id of the task of the entry found.
+ * @param histo: Input location for the model descriptor.
+ * @param bin: Bin id.
+ * @param cpu: CPU Id.
+ * @param vis_only: If true, a visible entry is requested.
+ * @param index: Optional output location for the index of the requested
+ *		 entry inside the array.
+ * @returns Process Id of the task if an entry has been found. Else a negative
+ *	    Identifier (KS_EMPTY_BIN or KS_FILTERED_BIN).
+ */
+int ksmodel_get_pid_front(struct kshark_trace_histo *histo,
+			  int bin, int cpu, bool vis_only,
+			  ssize_t *index)
+{
+	const struct kshark_entry *entry;
+
+	if (cpu < 0)
+		return KS_EMPTY_BIN;
+
+	entry = ksmodel_get_entry_front(histo, bin, vis_only,
+					       kshark_match_cpu, cpu,
+					       index);
+	return ksmodel_get_entry_pid(entry);
+}
+
+/**
+ * @brief In a given bin, start from the back end of the bin and go towards
+ *	  the front end, searching for an entry from a given CPU. Return
+ *	  the Process Id of the task of the entry found.
+ * @param histo: Input location for the model descriptor.
+ * @param bin: Bin id.
+ * @param cpu: CPU Id.
+ * @param vis_only: If true, a visible entry is requested.
+ * @param index: Optional output location for the index of the requested
+ *		 entry inside the array.
+ * @returns Process Id of the task if an entry has been found. Else a negative
+ *	    Identifier (KS_EMPTY_BIN or KS_FILTERED_BIN).
+ */
+int ksmodel_get_pid_back(struct kshark_trace_histo *histo,
+			 int bin, int cpu, bool vis_only,
+			 ssize_t *index)
+{
+	const struct kshark_entry *entry;
+
+	if (cpu < 0)
+		return KS_EMPTY_BIN;
+
+	entry = ksmodel_get_entry_back(histo, bin, vis_only,
+					      kshark_match_cpu, cpu,
+					      index);
+
+	return ksmodel_get_entry_pid(entry);
+}
+
+static int ksmodel_get_entry_cpu(const struct kshark_entry *entry)
+{
+	if (!entry) {
+		/* No data has been found. */
+		return KS_EMPTY_BIN;
+	}
+
+	/*
+	 * Note that if some data has been found, but this data is
+	 * filtered-outa, the Dummy entry is returned. The CPU Id of the Dummy
+	 * entry is KS_FILTERED_BIN.
+	 */
+
+	return entry->cpu;
+}
+
+/**
+ * @brief In a given bin, start from the front end of the bin and go towards
+ *	  the back end, searching for an entry from a given PID. Return
+ *	  the CPU Id of the entry found.
+ * @param histo: Input location for the model descriptor.
+ * @param bin: Bin id.
+ * @param pid: Process Id.
+ * @param vis_only: If true, a visible entry is requested.
+ * @param index: Optional output location for the index of the requested
+ *		 entry inside the array.
+ * @returns Process Id of the task if an entry has been found. Else a negative
+ *	    Identifier (KS_EMPTY_BIN or KS_FILTERED_BIN).
+ */
+int ksmodel_get_cpu_front(struct kshark_trace_histo *histo,
+			  int bin, int pid, bool vis_only,
+			  ssize_t *index)
+{
+	const struct kshark_entry *entry;
+
+	if (pid < 0)
+		return KS_EMPTY_BIN;
+
+	entry = ksmodel_get_entry_front(histo, bin, vis_only,
+					       kshark_match_pid, pid,
+					       index);
+	return ksmodel_get_entry_cpu(entry);
+}
+
+/**
+ * @brief In a given bin, start from the back end of the bin and go towards
+ *	  the front end, searching for an entry from a given PID. Return
+ *	  the CPU Id of the entry found.
+ * @param histo: Input location for the model descriptor.
+ * @param bin: Bin id.
+ * @param pid: Process Id.
+ * @param vis_only: If true, a visible entry is requested.
+ * @param index: Optional output location for the index of the requested
+ *		 entry inside the array.
+ * @returns Process Id of the task if an entry has been found. Else a negative
+ *	    Identifier (KS_EMPTY_BIN or KS_FILTERED_BIN).
+ */
+int ksmodel_get_cpu_back(struct kshark_trace_histo *histo,
+			 int bin, int pid, bool vis_only,
+			 ssize_t *index)
+{
+	const struct kshark_entry *entry;
+
+	if (pid < 0)
+		return KS_EMPTY_BIN;
+
+	entry = ksmodel_get_entry_back(histo, bin, vis_only,
+					      kshark_match_pid, pid,
+					      index);
+
+	return ksmodel_get_entry_cpu(entry);
+}
+
+/**
+ * @brief Check if a visible trace event from a given Cpu exists in this bin.
+ * @param histo: Input location for the model descriptor.
+ * @param bin: Bin id.
+ * @param cpu: Cpu Id.
+ * @param index: Optional output location for the index of the requested
+ *		 entry inside the array.
+ * @returns True, if a visible entry exists in this bin. Else false.
+ */
+bool ksmodel_cpu_visible_event_exist(struct kshark_trace_histo *histo,
+				     int bin, int cpu, ssize_t *index)
+{
+	struct kshark_entry_request *req;
+	const struct kshark_entry *entry;
+
+	if (index)
+		*index = KS_EMPTY_BIN;
+
+	/* Set the position at the beginning of the bin and go forward. */
+	req = ksmodel_entry_front_request_alloc(histo,
+						bin, true,
+						kshark_match_cpu, cpu);
+	if (!req)
+		return false;
+
+	/*
+	 * The default visibility mask of the Model Data request is
+	 * KS_GRAPH_VIEW_FILTER_MASK. Change the mask to
+	 * KS_EVENT_VIEW_FILTER_MASK because we want to find a visible event.
+	 */
+	req->vis_mask = KS_EVENT_VIEW_FILTER_MASK;
+
+	entry = kshark_get_entry_front(req, histo->data, index);
+	free(req);
+
+	if (!entry || !entry->visible) {
+		/* No visible entry has been found. */
+		return false;
+	}
+
+	return true;
+}
+
+/**
+ * @brief Check if a visible trace event from a given Task exists in this bin.
+ * @param histo: Input location for the model descriptor.
+ * @param bin: Bin id.
+ * @param pid: Process Id of the task.
+ * @param index: Optional output location for the index of the requested
+ *		 entry inside the array.
+ * @returns True, if a visible entry exists in this bin. Else false.
+ */
+bool ksmodel_task_visible_event_exist(struct kshark_trace_histo *histo,
+				      int bin, int pid, ssize_t *index)
+{
+	struct kshark_entry_request *req;
+	const struct kshark_entry *entry;
+
+	if (index)
+		*index = KS_EMPTY_BIN;
+
+	/* Set the position at the beginning of the bin and go forward. */
+	req = ksmodel_entry_front_request_alloc(histo,
+						bin, true,
+						kshark_match_pid, pid);
+	if (!req)
+		return false;
+
+	/*
+	 * The default visibility mask of the Model Data request is
+	 * KS_GRAPH_VIEW_FILTER_MASK. Change the mask to
+	 * KS_EVENT_VIEW_FILTER_MASK because we want to find a visible event.
+	 */
+	req->vis_mask = KS_EVENT_VIEW_FILTER_MASK;
+
+	entry = kshark_get_entry_front(req, histo->data, index);
+	free(req);
+
+	if (!entry || !entry->visible) {
+		/* No visible entry has been found. */
+		return false;
+	}
+
+	return true;
+}
diff --git a/kernel-shark-qt/src/libkshark-model.h b/kernel-shark-qt/src/libkshark-model.h
new file mode 100644
index 0000000..15391a9
--- /dev/null
+++ b/kernel-shark-qt/src/libkshark-model.h
@@ -0,0 +1,142 @@ 
+/* SPDX-License-Identifier: LGPL-2.1 */
+
+/*
+ * Copyright (C) 2017 VMware Inc, Yordan Karadzhov <[e-mail]>
+ */
+
+ /**
+  *  @file    libkshark-model.h
+  *  @brief   Visualization model for FTRACE (trace-cmd) data.
+  */
+
+#ifndef _LIB_KSHARK_MODEL_H
+#define _LIB_KSHARK_MODEL_H
+
+// KernelShark
+#include "libkshark.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+/** Overflow Bin identifiers. */
+enum OverflowBin {
+	/** Identifier of the Upper Overflow Bin. */
+	UPPER_OVERFLOW_BIN = -1,
+
+	/** Identifier of the Lower Overflow Bin. */
+	LOWER_OVERFLOW_BIN = -2,
+};
+
+/** Structure describing the current state of the visualization model. */
+struct kshark_trace_histo {
+	/** Trace data. */
+	struct kshark_entry	**data;
+
+	/** The size of the data. */
+	size_t			data_size;
+
+	/** The index of the first entry in each bin. */
+	ssize_t			*map;
+
+	/** Number of entries in each bin. */
+	size_t			*bin_count;
+
+	/** Lower edge of the time-window to be visualized. */
+	uint64_t		min;
+
+	/** Upper edge of the time-window to be visualized. */
+	uint64_t		max;
+
+	/** The size of the bins. */
+	uint64_t		bin_size;
+
+	/** Number of bins. */
+	int			n_bins;
+};
+
+void ksmodel_init(struct kshark_trace_histo *histo);
+
+void ksmodel_clear(struct kshark_trace_histo *histo);
+
+void ksmodel_set_bining(struct kshark_trace_histo *histo,
+			size_t n, uint64_t min, uint64_t max);
+
+void ksmodel_fill(struct kshark_trace_histo *histo,
+		  struct kshark_entry **data, size_t n);
+
+size_t ksmodel_bin_count(struct kshark_trace_histo *histo, int bin);
+
+void ksmodel_shift_forward(struct kshark_trace_histo *histo, size_t n);
+
+void ksmodel_shift_backward(struct kshark_trace_histo *histo, size_t n);
+
+void ksmodel_jump_to(struct kshark_trace_histo *histo, size_t ts);
+
+void ksmodel_zoom_out(struct kshark_trace_histo *histo,
+		      double r, int mark);
+
+void ksmodel_zoom_in(struct kshark_trace_histo *histo,
+		     double r, int mark);
+
+ssize_t ksmodel_first_index_at_bin(struct kshark_trace_histo *histo, int bin);
+
+ssize_t ksmodel_last_index_at_bin(struct kshark_trace_histo *histo, int bin);
+
+ssize_t ksmodel_first_index_at_cpu(struct kshark_trace_histo *histo,
+				   int bin, int cpu);
+
+ssize_t ksmodel_first_index_at_pid(struct kshark_trace_histo *histo,
+				   int bin, int pid);
+
+const struct kshark_entry *
+ksmodel_get_entry_front(struct kshark_trace_histo *histo,
+			int bin, bool vis_only,
+			matching_condition_func func, int val,
+			ssize_t *index);
+
+const struct kshark_entry *
+ksmodel_get_entry_back(struct kshark_trace_histo *histo,
+		       int bin, bool vis_only,
+		       matching_condition_func func, int val,
+		       ssize_t *index);
+
+int ksmodel_get_pid_front(struct kshark_trace_histo *histo,
+			  int bin, int cpu, bool vis_only,
+			  ssize_t *index);
+
+int ksmodel_get_pid_back(struct kshark_trace_histo *histo,
+			 int bin, int cpu, bool vis_only,
+			 ssize_t *index);
+
+int ksmodel_get_cpu_front(struct kshark_trace_histo *histo,
+			  int bin, int pid, bool vis_only,
+			  ssize_t *index);
+
+int ksmodel_get_cpu_back(struct kshark_trace_histo *histo,
+			 int bin, int pid, bool vis_only,
+			 ssize_t *index);
+
+bool ksmodel_cpu_visible_event_exist(struct kshark_trace_histo *histo,
+				     int bin, int cpu, ssize_t *index);
+
+bool ksmodel_task_visible_event_exist(struct kshark_trace_histo *histo,
+				      int bin, int pid, ssize_t *index);
+
+static inline double ksmodel_bin_time(struct kshark_trace_histo *histo,
+				      int bin)
+{
+	return (histo->min + bin*histo->bin_size) * 1e-9;
+}
+
+static inline uint64_t ksmodel_bin_ts(struct kshark_trace_histo *histo,
+				      int bin)
+{
+	return (histo->min + bin*histo->bin_size);
+}
+
+#ifdef __cplusplus
+}
+#endif // __cplusplus
+
+#endif