[35/54] tracing: Add cpu field for hist triggers
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Message ID TY1PR01MB1692705692B04316012D3FC796090@TY1PR01MB1692.jpnprd01.prod.outlook.com
State New
Headers show
Series
  • Untitled series #12765
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Commit Message

Motai.Hirotaka@aj.MitsubishiElectric.co.jp Aug. 29, 2018, 12:17 p.m. UTC
A common key to use in a histogram is the cpuid - add a new cpu
'synthetic' field named 'cpu' for that purpose.

Link: http://lkml.kernel.org/r/89537645bfc957e0d76e2cacf5f0ada88691a6cc.1516069914.git.tom.zanussi@linux.intel.com

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
(cherry picked from commit 8b7622bf94a44b3f912e6492bf500e86171300b8)
Signed-off-by: Hirotaka MOTAI <Motai.Hirotaka@aj.MitsubishiElectric.co.jp>
---
 Documentation/trace/histogram.txt | 15 +++++++++++++++
 kernel/trace/trace_events_hist.c  | 28 +++++++++++++++++++++++++++-
 2 files changed, 42 insertions(+), 1 deletion(-)

Patch
diff mbox series

diff --git a/Documentation/trace/histogram.txt b/Documentation/trace/histogram.txt
index 25c94730..be612ca7 100644
--- a/Documentation/trace/histogram.txt
+++ b/Documentation/trace/histogram.txt
@@ -167,16 +167,31 @@ 
   The above sets up an initially paused hist trigger which is unpaused
   and starts aggregating events when a given program is executed, and
   which stops aggregating when the process exits and the hist trigger
   is paused again.
 
   The examples below provide a more concrete illustration of the
   concepts and typical usage patterns discussed above.
 
+  'special' event fields
+  ------------------------
+
+  There are a number of 'special event fields' available for use as
+  keys or values in a hist trigger.  These look like and behave as if
+  they were actual event fields, but aren't really part of the event's
+  field definition or format file.  They are however available for any
+  event, and can be used anywhere an actual event field could be.
+  They are:
+
+    common_timestamp       u64 - timestamp (from ring buffer) associated
+                                 with the event, in nanoseconds.  May be
+				 modified by .usecs to have timestamps
+				 interpreted as microseconds.
+    cpu                    int - the cpu on which the event occurred.
 
 6.2 'hist' trigger examples
 ---------------------------
 
   The first set of examples creates aggregations using the kmalloc
   event.  The fields that can be used for the hist trigger are listed
   in the kmalloc event's format file:
 
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 7e88daae..98be6ad8 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -222,16 +222,17 @@  enum hist_field_flags {
 	HIST_FIELD_FL_SYSCALL		= 1 << 7,
 	HIST_FIELD_FL_STACKTRACE	= 1 << 8,
 	HIST_FIELD_FL_LOG2		= 1 << 9,
 	HIST_FIELD_FL_TIMESTAMP		= 1 << 10,
 	HIST_FIELD_FL_TIMESTAMP_USECS	= 1 << 11,
 	HIST_FIELD_FL_VAR		= 1 << 12,
 	HIST_FIELD_FL_EXPR		= 1 << 13,
 	HIST_FIELD_FL_VAR_REF		= 1 << 14,
+	HIST_FIELD_FL_CPU		= 1 << 15,
 };
 
 struct var_defs {
 	unsigned int	n_vars;
 	char		*name[TRACING_MAP_VARS_MAX];
 	char		*expr[TRACING_MAP_VARS_MAX];
 };
 
@@ -1159,16 +1160,26 @@  static u64 hist_field_timestamp(struct hist_field *hist_field,
 	u64 ts = ring_buffer_event_time_stamp(rbe);
 
 	if (hist_data->attrs->ts_in_usecs && trace_clock_in_ns(tr))
 		ts = ns2usecs(ts);
 
 	return ts;
 }
 
+static u64 hist_field_cpu(struct hist_field *hist_field,
+			  struct tracing_map_elt *elt,
+			  struct ring_buffer_event *rbe,
+			  void *event)
+{
+	int cpu = smp_processor_id();
+
+	return cpu;
+}
+
 static struct hist_field *
 check_field_for_var_ref(struct hist_field *hist_field,
 			struct hist_trigger_data *var_data,
 			unsigned int var_idx)
 {
 	struct hist_field *found = NULL;
 
 	if (hist_field && hist_field->flags & HIST_FIELD_FL_VAR_REF) {
@@ -1597,16 +1608,18 @@  static const char *hist_field_name(struct hist_field *field,
 		return field_name;
 
 	if (field->field)
 		field_name = field->field->name;
 	else if (field->flags & HIST_FIELD_FL_LOG2)
 		field_name = hist_field_name(field->operands[0], ++level);
 	else if (field->flags & HIST_FIELD_FL_TIMESTAMP)
 		field_name = "common_timestamp";
+	else if (field->flags & HIST_FIELD_FL_CPU)
+		field_name = "cpu";
 	else if (field->flags & HIST_FIELD_FL_EXPR ||
 		 field->flags & HIST_FIELD_FL_VAR_REF) {
 		if (field->system) {
 			static char full_name[MAX_FILTER_STR_VAL];
 
 			strcat(full_name, field->system);
 			strcat(full_name, ".");
 			strcat(full_name, field->event_name);
@@ -2104,16 +2117,25 @@  static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
 		hist_field->fn = hist_field_timestamp;
 		hist_field->size = sizeof(u64);
 		hist_field->type = kstrdup("u64", GFP_KERNEL);
 		if (!hist_field->type)
 			goto free;
 		goto out;
 	}
 
+	if (flags & HIST_FIELD_FL_CPU) {
+		hist_field->fn = hist_field_cpu;
+		hist_field->size = sizeof(int);
+		hist_field->type = kstrdup("unsigned int", GFP_KERNEL);
+		if (!hist_field->type)
+			goto free;
+		goto out;
+	}
+
 	if (WARN_ON_ONCE(!field))
 		goto out;
 
 	if (is_string_field(field)) {
 		flags |= HIST_FIELD_FL_STRING;
 
 		hist_field->size = MAX_FILTER_STR_VAL;
 		hist_field->type = kstrdup(field->type, GFP_KERNEL);
@@ -2340,17 +2362,19 @@  parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file,
 		}
 	}
 
 	if (strcmp(field_name, "common_timestamp") == 0) {
 		*flags |= HIST_FIELD_FL_TIMESTAMP;
 		hist_data->enable_timestamps = true;
 		if (*flags & HIST_FIELD_FL_TIMESTAMP_USECS)
 			hist_data->attrs->ts_in_usecs = true;
-	} else {
+	} else if (strcmp(field_name, "cpu") == 0)
+		*flags |= HIST_FIELD_FL_CPU;
+	else {
 		field = trace_find_event_field(file->event_call, field_name);
 		if (!field || !field->size) {
 			field = ERR_PTR(-EINVAL);
 			goto out;
 		}
 	}
  out:
 	kfree(str);
@@ -4614,16 +4638,18 @@  static void hist_field_print(struct seq_file *m, struct hist_field *hist_field)
 {
 	const char *field_name = hist_field_name(hist_field, 0);
 
 	if (hist_field->var.name)
 		seq_printf(m, "%s=", hist_field->var.name);
 
 	if (hist_field->flags & HIST_FIELD_FL_TIMESTAMP)
 		seq_puts(m, "common_timestamp");
+	else if (hist_field->flags & HIST_FIELD_FL_CPU)
+		seq_puts(m, "cpu");
 	else if (field_name) {
 		if (hist_field->flags & HIST_FIELD_FL_VAR_REF)
 			seq_putc(m, '$');
 		seq_printf(m, "%s", field_name);
 	}
 
 	if (hist_field->flags) {
 		const char *flags_str = get_hist_field_flags(hist_field);