[v1,3/5] perf cs-etm: Support for NO_SYNC packet
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Message ID 1541912383-19915-4-git-send-email-leo.yan@linaro.org
State New
Headers show
Series
  • perf cs-etm: Correct packets handling
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Commit Message

Leo Yan Nov. 11, 2018, 4:59 a.m. UTC
As described in OpenCSD (CoreSight decoder lib), in the decoding stream
it includes one trace element with type OCSD_GEN_TRC_ELEM_NO_SYNC; the
element indicates 'either at start of decode, or after overflow / bad
packet', we should take it as a signal for the tracing off and this will
cause tracing discontinuity.  From the trace dump with 'perf script',
sometimes the element OCSD_GEN_TRC_ELEM_NO_SYNC collaborates with
element OCSD_GEN_TRC_ELEM_TRACE_ON to show the tracing flow have been
turned off and on, in this case the cs-etm code has handled TRACE_ON
packet well so we observe the tracing discontinuity; but in another case
it only inserts the element OCSD_GEN_TRC_ELEM_NO_SYNC into instructions
packets, we miss to handle the case if has only standalone NO_SYNC
element and users cannot receive the info for tracing discontinuity.

This patch introduces new type CS_ETM_TRACE_OFF to generate packet for
receiving element OCSD_GEN_TRC_ELEM_NO_SYNC from decoder; when generate
sample, CS_ETM_TRACE_OFF packet has almost the same behaviour with
CS_ETM_TRACE_ON packet: both of them invokes cs_etm__flush() to generate
samples for the previous instructions packet, and in cs_etm__sample() it
also needs to generate samples if TRACE_OFF packet is followed by one
sequential instructions packet.  This patch also converts the address to
0 for TRACE_OFF packet, this is same with TRACE_ON packet as well.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
 tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 10 ++++++++++
 tools/perf/util/cs-etm-decoder/cs-etm-decoder.h |  7 ++++---
 tools/perf/util/cs-etm.c                        | 15 +++++++++++----
 3 files changed, 25 insertions(+), 7 deletions(-)

Comments

Mathieu Poirier Nov. 19, 2018, 6:27 p.m. UTC | #1
On Sun, Nov 11, 2018 at 12:59:41PM +0800, Leo Yan wrote:
> As described in OpenCSD (CoreSight decoder lib), in the decoding stream
> it includes one trace element with type OCSD_GEN_TRC_ELEM_NO_SYNC; the
> element indicates 'either at start of decode, or after overflow / bad
> packet', we should take it as a signal for the tracing off and this will
> cause tracing discontinuity.  From the trace dump with 'perf script',
> sometimes the element OCSD_GEN_TRC_ELEM_NO_SYNC collaborates with
> element OCSD_GEN_TRC_ELEM_TRACE_ON to show the tracing flow have been
> turned off and on, in this case the cs-etm code has handled TRACE_ON
> packet well so we observe the tracing discontinuity; but in another case
> it only inserts the element OCSD_GEN_TRC_ELEM_NO_SYNC into instructions
> packets, we miss to handle the case if has only standalone NO_SYNC
> element and users cannot receive the info for tracing discontinuity.
> 
> This patch introduces new type CS_ETM_TRACE_OFF to generate packet for
> receiving element OCSD_GEN_TRC_ELEM_NO_SYNC from decoder; when generate
> sample, CS_ETM_TRACE_OFF packet has almost the same behaviour with

Here you have used the word "almost", leading me to beleive there are cases
where the handling of TRACE_ON and NO_SYNC packets differ, but the
implementation enacts the same behavior for both.

Mike or Robert, can you confirm that TRACE_ON and NO_SYNC packets should be
treated the same way?

Leo, if handling of the TRACE_ON and NO_SYNC packets is the same then we should
treat them the same way in cs_etm_decoder__gen_trace_elem_printer(), i.e simply
call cs_etm_decoder__buffer_trace_on().  That way packet handling in cs-etm.c
doesn't change.  Otherwise see my comments below.

> CS_ETM_TRACE_ON packet: both of them invokes cs_etm__flush() to generate
> samples for the previous instructions packet, and in cs_etm__sample() it
> also needs to generate samples if TRACE_OFF packet is followed by one
> sequential instructions packet.  This patch also converts the address to
> 0 for TRACE_OFF packet, this is same with TRACE_ON packet as well.
> 
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
> ---
>  tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 10 ++++++++++
>  tools/perf/util/cs-etm-decoder/cs-etm-decoder.h |  7 ++++---
>  tools/perf/util/cs-etm.c                        | 15 +++++++++++----
>  3 files changed, 25 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> index 5efb616..9d52727 100644
> --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> @@ -369,6 +369,14 @@ cs_etm_decoder__buffer_range(struct cs_etm_decoder *decoder,
>  }
>  
>  static ocsd_datapath_resp_t
> +cs_etm_decoder__buffer_trace_off(struct cs_etm_decoder *decoder,
> +				 const uint8_t trace_chan_id)
> +{
> +	return cs_etm_decoder__buffer_packet(decoder, trace_chan_id,
> +					     CS_ETM_TRACE_OFF);
> +}
> +
> +static ocsd_datapath_resp_t
>  cs_etm_decoder__buffer_trace_on(struct cs_etm_decoder *decoder,
>  				const uint8_t trace_chan_id)
>  {
> @@ -389,6 +397,8 @@ static ocsd_datapath_resp_t cs_etm_decoder__gen_trace_elem_printer(
>  	case OCSD_GEN_TRC_ELEM_UNKNOWN:
>  		break;
>  	case OCSD_GEN_TRC_ELEM_NO_SYNC:
> +		resp = cs_etm_decoder__buffer_trace_off(decoder,
> +							trace_chan_id);

If we want to handle NO_SYNC element types, why introduce a "trace_off"
function?  Wouldn't it make more sense to call it
cs_etm_decoder__buffer_no_sync() ?

>  		decoder->trace_on = false;
>  		break;
>  	case OCSD_GEN_TRC_ELEM_TRACE_ON:
> diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> index 9351bd1..a38c97c 100644
> --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> @@ -23,9 +23,10 @@ struct cs_etm_buffer {
>  };
>  
>  enum cs_etm_sample_type {
> -	CS_ETM_EMPTY = 0,
> -	CS_ETM_RANGE = 1 << 0,
> -	CS_ETM_TRACE_ON = 1 << 1,
> +	CS_ETM_EMPTY		= 0,
> +	CS_ETM_RANGE		= 1 << 0,
> +	CS_ETM_TRACE_ON		= 1 << 1,
> +	CS_ETM_TRACE_OFF	= 1 << 2,

CS_ETM_NO_SYNC, see above comment.  And please don't use indentation.


>  };
>  
>  enum cs_etm_isa {
> diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> index f4fa877..2a0cef9 100644
> --- a/tools/perf/util/cs-etm.c
> +++ b/tools/perf/util/cs-etm.c
> @@ -517,8 +517,9 @@ static inline int cs_etm__t32_instr_size(struct cs_etm_queue *etmq,
>  
>  static inline u64 cs_etm__first_executed_instr(struct cs_etm_packet *packet)
>  {
> -	/* Returns 0 for the CS_ETM_TRACE_ON packet */
> -	if (packet->sample_type == CS_ETM_TRACE_ON)
> +	/* Returns 0 for TRACE_ON and TRACE_OFF packets */
> +	if (packet->sample_type == CS_ETM_TRACE_ON ||
> +	    packet->sample_type == CS_ETM_TRACE_OFF)
>  		return 0;
>  
>  	return packet->start_addr;
> @@ -527,8 +528,9 @@ static inline u64 cs_etm__first_executed_instr(struct cs_etm_packet *packet)
>  static inline
>  u64 cs_etm__last_executed_instr(const struct cs_etm_packet *packet)
>  {
> -	/* Returns 0 for the CS_ETM_TRACE_ON packet */
> -	if (packet->sample_type == CS_ETM_TRACE_ON)
> +	/* Returns 0 for TRACE_ON and TRACE_OFF packets */
> +	if (packet->sample_type == CS_ETM_TRACE_ON ||
> +	    packet->sample_type == CS_ETM_TRACE_OFF)
>  		return 0;
>  
>  	return packet->end_addr - packet->last_instr_size;
> @@ -930,6 +932,10 @@ static int cs_etm__sample(struct cs_etm_queue *etmq)
>  		if (etmq->prev_packet->sample_type == CS_ETM_TRACE_ON)
>  			generate_sample = true;
>  
> +		/* Generate sample for tracing off packet */
> +		if (etmq->prev_packet->sample_type == CS_ETM_TRACE_OFF)
> +			generate_sample = true;
> +
>  		/* Generate sample for branch taken packet */
>  		if (etmq->prev_packet->sample_type == CS_ETM_RANGE &&
>  		    etmq->prev_packet->last_instr_taken_branch)
> @@ -1085,6 +1091,7 @@ static int cs_etm__run_decoder(struct cs_etm_queue *etmq)
>  					cs_etm__sample(etmq);
>  					break;
>  				case CS_ETM_TRACE_ON:
> +				case CS_ETM_TRACE_OFF:
>  					/*
>  					 * Discontinuity in trace, flush
>  					 * previous branch stack
> -- 
> 2.7.4
>
Leo Yan Dec. 5, 2018, 3:31 a.m. UTC | #2
On Mon, Nov 19, 2018 at 11:27:59AM -0700, Mathieu Poirier wrote:
> On Sun, Nov 11, 2018 at 12:59:41PM +0800, Leo Yan wrote:
> > As described in OpenCSD (CoreSight decoder lib), in the decoding stream
> > it includes one trace element with type OCSD_GEN_TRC_ELEM_NO_SYNC; the
> > element indicates 'either at start of decode, or after overflow / bad
> > packet', we should take it as a signal for the tracing off and this will
> > cause tracing discontinuity.  From the trace dump with 'perf script',
> > sometimes the element OCSD_GEN_TRC_ELEM_NO_SYNC collaborates with
> > element OCSD_GEN_TRC_ELEM_TRACE_ON to show the tracing flow have been
> > turned off and on, in this case the cs-etm code has handled TRACE_ON
> > packet well so we observe the tracing discontinuity; but in another case
> > it only inserts the element OCSD_GEN_TRC_ELEM_NO_SYNC into instructions
> > packets, we miss to handle the case if has only standalone NO_SYNC
> > element and users cannot receive the info for tracing discontinuity.
> > 
> > This patch introduces new type CS_ETM_TRACE_OFF to generate packet for
> > receiving element OCSD_GEN_TRC_ELEM_NO_SYNC from decoder; when generate
> > sample, CS_ETM_TRACE_OFF packet has almost the same behaviour with
> 
> Here you have used the word "almost", leading me to beleive there are cases
> where the handling of TRACE_ON and NO_SYNC packets differ, but the
> implementation enacts the same behavior for both.
> 
> Mike or Robert, can you confirm that TRACE_ON and NO_SYNC packets should be
> treated the same way?

I also would like to get suggestions/comments from Mike and Rob.

For NO_SYNC packet, Mike before has given some explination for it:

"looking at the decoder flow, when the decoder is reset, then it is
returned to an unsynchronised state and a NO_SYNC will be output.
With perf, it can concatenate multiple trace buffers into a single
section of the perf.data file. To ensure that the decode process can
see the start of a new buffer, the drivers will insert a barrier
packet between different buffers so that the decoder can spot the
boundaries. When the decoder hits a barrier packet it will
automatically reset so that it correctly decodes the next trace
buffer. This could be what you are seeing here."

So I think there still have some difference between TRACE_ON and
NO_SYNC packets, TRACE_ON packet indicates the start of trace and it's
also possible caused by tracing discontinuity; NO_SYNC packets usually
caused by an unsynchronised state.  But both of them presents
discontinuity in perf trace data.

I prefer to use two different packet types to present them, this can
let the code to be more readable and easier to be maintained later.

If you agree with this, I also will rephrase the commit log to avoid
confusion that these two packets are the same thing.

> Leo, if handling of the TRACE_ON and NO_SYNC packets is the same then we should
> treat them the same way in cs_etm_decoder__gen_trace_elem_printer(), i.e simply
> call cs_etm_decoder__buffer_trace_on().  That way packet handling in cs-etm.c
> doesn't change.  Otherwise see my comments below.
> 
> > CS_ETM_TRACE_ON packet: both of them invokes cs_etm__flush() to generate
> > samples for the previous instructions packet, and in cs_etm__sample() it
> > also needs to generate samples if TRACE_OFF packet is followed by one
> > sequential instructions packet.  This patch also converts the address to
> > 0 for TRACE_OFF packet, this is same with TRACE_ON packet as well.
> > 
> > Signed-off-by: Leo Yan <leo.yan@linaro.org>
> > ---
> >  tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 10 ++++++++++
> >  tools/perf/util/cs-etm-decoder/cs-etm-decoder.h |  7 ++++---
> >  tools/perf/util/cs-etm.c                        | 15 +++++++++++----
> >  3 files changed, 25 insertions(+), 7 deletions(-)
> > 
> > diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> > index 5efb616..9d52727 100644
> > --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> > +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> > @@ -369,6 +369,14 @@ cs_etm_decoder__buffer_range(struct cs_etm_decoder *decoder,
> >  }
> >  
> >  static ocsd_datapath_resp_t
> > +cs_etm_decoder__buffer_trace_off(struct cs_etm_decoder *decoder,
> > +				 const uint8_t trace_chan_id)
> > +{
> > +	return cs_etm_decoder__buffer_packet(decoder, trace_chan_id,
> > +					     CS_ETM_TRACE_OFF);
> > +}
> > +
> > +static ocsd_datapath_resp_t
> >  cs_etm_decoder__buffer_trace_on(struct cs_etm_decoder *decoder,
> >  				const uint8_t trace_chan_id)
> >  {
> > @@ -389,6 +397,8 @@ static ocsd_datapath_resp_t cs_etm_decoder__gen_trace_elem_printer(
> >  	case OCSD_GEN_TRC_ELEM_UNKNOWN:
> >  		break;
> >  	case OCSD_GEN_TRC_ELEM_NO_SYNC:
> > +		resp = cs_etm_decoder__buffer_trace_off(decoder,
> > +							trace_chan_id);
> 
> If we want to handle NO_SYNC element types, why introduce a "trace_off"
> function?  Wouldn't it make more sense to call it
> cs_etm_decoder__buffer_no_sync() ?

Will change to cs_etm_decoder__buffer_no_sync().

> >  		decoder->trace_on = false;
> >  		break;
> >  	case OCSD_GEN_TRC_ELEM_TRACE_ON:
> > diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> > index 9351bd1..a38c97c 100644
> > --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> > +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> > @@ -23,9 +23,10 @@ struct cs_etm_buffer {
> >  };
> >  
> >  enum cs_etm_sample_type {
> > -	CS_ETM_EMPTY = 0,
> > -	CS_ETM_RANGE = 1 << 0,
> > -	CS_ETM_TRACE_ON = 1 << 1,
> > +	CS_ETM_EMPTY		= 0,
> > +	CS_ETM_RANGE		= 1 << 0,
> > +	CS_ETM_TRACE_ON		= 1 << 1,
> > +	CS_ETM_TRACE_OFF	= 1 << 2,
> 
> CS_ETM_NO_SYNC, see above comment.  And please don't use indentation.

Will do this.

> >  };
> >  
> >  enum cs_etm_isa {
> > diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> > index f4fa877..2a0cef9 100644
> > --- a/tools/perf/util/cs-etm.c
> > +++ b/tools/perf/util/cs-etm.c
> > @@ -517,8 +517,9 @@ static inline int cs_etm__t32_instr_size(struct cs_etm_queue *etmq,
> >  
> >  static inline u64 cs_etm__first_executed_instr(struct cs_etm_packet *packet)
> >  {
> > -	/* Returns 0 for the CS_ETM_TRACE_ON packet */
> > -	if (packet->sample_type == CS_ETM_TRACE_ON)
> > +	/* Returns 0 for TRACE_ON and TRACE_OFF packets */
> > +	if (packet->sample_type == CS_ETM_TRACE_ON ||
> > +	    packet->sample_type == CS_ETM_TRACE_OFF)
> >  		return 0;
> >  
> >  	return packet->start_addr;
> > @@ -527,8 +528,9 @@ static inline u64 cs_etm__first_executed_instr(struct cs_etm_packet *packet)
> >  static inline
> >  u64 cs_etm__last_executed_instr(const struct cs_etm_packet *packet)
> >  {
> > -	/* Returns 0 for the CS_ETM_TRACE_ON packet */
> > -	if (packet->sample_type == CS_ETM_TRACE_ON)
> > +	/* Returns 0 for TRACE_ON and TRACE_OFF packets */
> > +	if (packet->sample_type == CS_ETM_TRACE_ON ||
> > +	    packet->sample_type == CS_ETM_TRACE_OFF)
> >  		return 0;
> >  
> >  	return packet->end_addr - packet->last_instr_size;
> > @@ -930,6 +932,10 @@ static int cs_etm__sample(struct cs_etm_queue *etmq)
> >  		if (etmq->prev_packet->sample_type == CS_ETM_TRACE_ON)
> >  			generate_sample = true;
> >  
> > +		/* Generate sample for tracing off packet */
> > +		if (etmq->prev_packet->sample_type == CS_ETM_TRACE_OFF)
> > +			generate_sample = true;
> > +
> >  		/* Generate sample for branch taken packet */
> >  		if (etmq->prev_packet->sample_type == CS_ETM_RANGE &&
> >  		    etmq->prev_packet->last_instr_taken_branch)
> > @@ -1085,6 +1091,7 @@ static int cs_etm__run_decoder(struct cs_etm_queue *etmq)
> >  					cs_etm__sample(etmq);
> >  					break;
> >  				case CS_ETM_TRACE_ON:
> > +				case CS_ETM_TRACE_OFF:
> >  					/*
> >  					 * Discontinuity in trace, flush
> >  					 * previous branch stack
> > -- 
> > 2.7.4
> >
Mathieu Poirier Dec. 5, 2018, 5:48 p.m. UTC | #3
On Tue, 4 Dec 2018 at 20:31, <leo.yan@linaro.org> wrote:
>
> On Mon, Nov 19, 2018 at 11:27:59AM -0700, Mathieu Poirier wrote:
> > On Sun, Nov 11, 2018 at 12:59:41PM +0800, Leo Yan wrote:
> > > As described in OpenCSD (CoreSight decoder lib), in the decoding stream
> > > it includes one trace element with type OCSD_GEN_TRC_ELEM_NO_SYNC; the
> > > element indicates 'either at start of decode, or after overflow / bad
> > > packet', we should take it as a signal for the tracing off and this will
> > > cause tracing discontinuity.  From the trace dump with 'perf script',
> > > sometimes the element OCSD_GEN_TRC_ELEM_NO_SYNC collaborates with
> > > element OCSD_GEN_TRC_ELEM_TRACE_ON to show the tracing flow have been
> > > turned off and on, in this case the cs-etm code has handled TRACE_ON
> > > packet well so we observe the tracing discontinuity; but in another case
> > > it only inserts the element OCSD_GEN_TRC_ELEM_NO_SYNC into instructions
> > > packets, we miss to handle the case if has only standalone NO_SYNC
> > > element and users cannot receive the info for tracing discontinuity.
> > >
> > > This patch introduces new type CS_ETM_TRACE_OFF to generate packet for
> > > receiving element OCSD_GEN_TRC_ELEM_NO_SYNC from decoder; when generate
> > > sample, CS_ETM_TRACE_OFF packet has almost the same behaviour with
> >
> > Here you have used the word "almost", leading me to beleive there are cases
> > where the handling of TRACE_ON and NO_SYNC packets differ, but the
> > implementation enacts the same behavior for both.
> >
> > Mike or Robert, can you confirm that TRACE_ON and NO_SYNC packets should be
> > treated the same way?
>
> I also would like to get suggestions/comments from Mike and Rob.
>
> For NO_SYNC packet, Mike before has given some explination for it:
>
> "looking at the decoder flow, when the decoder is reset, then it is
> returned to an unsynchronised state and a NO_SYNC will be output.
> With perf, it can concatenate multiple trace buffers into a single
> section of the perf.data file. To ensure that the decode process can
> see the start of a new buffer, the drivers will insert a barrier
> packet between different buffers so that the decoder can spot the
> boundaries. When the decoder hits a barrier packet it will
> automatically reset so that it correctly decodes the next trace
> buffer. This could be what you are seeing here."
>
> So I think there still have some difference between TRACE_ON and
> NO_SYNC packets, TRACE_ON packet indicates the start of trace and it's
> also possible caused by tracing discontinuity; NO_SYNC packets usually
> caused by an unsynchronised state.  But both of them presents
> discontinuity in perf trace data.
>
> I prefer to use two different packet types to present them, this can
> let the code to be more readable and easier to be maintained later.

Absolutely.  Make sure to get to the bottom of the story with Mike
and/or Robert before sending your next patchset.

>
> If you agree with this, I also will rephrase the commit log to avoid
> confusion that these two packets are the same thing.

Yes please.

>
> > Leo, if handling of the TRACE_ON and NO_SYNC packets is the same then we should
> > treat them the same way in cs_etm_decoder__gen_trace_elem_printer(), i.e simply
> > call cs_etm_decoder__buffer_trace_on().  That way packet handling in cs-etm.c
> > doesn't change.  Otherwise see my comments below.
> >
> > > CS_ETM_TRACE_ON packet: both of them invokes cs_etm__flush() to generate
> > > samples for the previous instructions packet, and in cs_etm__sample() it
> > > also needs to generate samples if TRACE_OFF packet is followed by one
> > > sequential instructions packet.  This patch also converts the address to
> > > 0 for TRACE_OFF packet, this is same with TRACE_ON packet as well.
> > >
> > > Signed-off-by: Leo Yan <leo.yan@linaro.org>
> > > ---
> > >  tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 10 ++++++++++
> > >  tools/perf/util/cs-etm-decoder/cs-etm-decoder.h |  7 ++++---
> > >  tools/perf/util/cs-etm.c                        | 15 +++++++++++----
> > >  3 files changed, 25 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> > > index 5efb616..9d52727 100644
> > > --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> > > +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> > > @@ -369,6 +369,14 @@ cs_etm_decoder__buffer_range(struct cs_etm_decoder *decoder,
> > >  }
> > >
> > >  static ocsd_datapath_resp_t
> > > +cs_etm_decoder__buffer_trace_off(struct cs_etm_decoder *decoder,
> > > +                            const uint8_t trace_chan_id)
> > > +{
> > > +   return cs_etm_decoder__buffer_packet(decoder, trace_chan_id,
> > > +                                        CS_ETM_TRACE_OFF);
> > > +}
> > > +
> > > +static ocsd_datapath_resp_t
> > >  cs_etm_decoder__buffer_trace_on(struct cs_etm_decoder *decoder,
> > >                             const uint8_t trace_chan_id)
> > >  {
> > > @@ -389,6 +397,8 @@ static ocsd_datapath_resp_t cs_etm_decoder__gen_trace_elem_printer(
> > >     case OCSD_GEN_TRC_ELEM_UNKNOWN:
> > >             break;
> > >     case OCSD_GEN_TRC_ELEM_NO_SYNC:
> > > +           resp = cs_etm_decoder__buffer_trace_off(decoder,
> > > +                                                   trace_chan_id);
> >
> > If we want to handle NO_SYNC element types, why introduce a "trace_off"
> > function?  Wouldn't it make more sense to call it
> > cs_etm_decoder__buffer_no_sync() ?
>
> Will change to cs_etm_decoder__buffer_no_sync().
>
> > >             decoder->trace_on = false;
> > >             break;
> > >     case OCSD_GEN_TRC_ELEM_TRACE_ON:
> > > diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> > > index 9351bd1..a38c97c 100644
> > > --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> > > +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> > > @@ -23,9 +23,10 @@ struct cs_etm_buffer {
> > >  };
> > >
> > >  enum cs_etm_sample_type {
> > > -   CS_ETM_EMPTY = 0,
> > > -   CS_ETM_RANGE = 1 << 0,
> > > -   CS_ETM_TRACE_ON = 1 << 1,
> > > +   CS_ETM_EMPTY            = 0,
> > > +   CS_ETM_RANGE            = 1 << 0,
> > > +   CS_ETM_TRACE_ON         = 1 << 1,
> > > +   CS_ETM_TRACE_OFF        = 1 << 2,
> >
> > CS_ETM_NO_SYNC, see above comment.  And please don't use indentation.
>
> Will do this.
>
> > >  };
> > >
> > >  enum cs_etm_isa {
> > > diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> > > index f4fa877..2a0cef9 100644
> > > --- a/tools/perf/util/cs-etm.c
> > > +++ b/tools/perf/util/cs-etm.c
> > > @@ -517,8 +517,9 @@ static inline int cs_etm__t32_instr_size(struct cs_etm_queue *etmq,
> > >
> > >  static inline u64 cs_etm__first_executed_instr(struct cs_etm_packet *packet)
> > >  {
> > > -   /* Returns 0 for the CS_ETM_TRACE_ON packet */
> > > -   if (packet->sample_type == CS_ETM_TRACE_ON)
> > > +   /* Returns 0 for TRACE_ON and TRACE_OFF packets */
> > > +   if (packet->sample_type == CS_ETM_TRACE_ON ||
> > > +       packet->sample_type == CS_ETM_TRACE_OFF)
> > >             return 0;
> > >
> > >     return packet->start_addr;
> > > @@ -527,8 +528,9 @@ static inline u64 cs_etm__first_executed_instr(struct cs_etm_packet *packet)
> > >  static inline
> > >  u64 cs_etm__last_executed_instr(const struct cs_etm_packet *packet)
> > >  {
> > > -   /* Returns 0 for the CS_ETM_TRACE_ON packet */
> > > -   if (packet->sample_type == CS_ETM_TRACE_ON)
> > > +   /* Returns 0 for TRACE_ON and TRACE_OFF packets */
> > > +   if (packet->sample_type == CS_ETM_TRACE_ON ||
> > > +       packet->sample_type == CS_ETM_TRACE_OFF)
> > >             return 0;
> > >
> > >     return packet->end_addr - packet->last_instr_size;
> > > @@ -930,6 +932,10 @@ static int cs_etm__sample(struct cs_etm_queue *etmq)
> > >             if (etmq->prev_packet->sample_type == CS_ETM_TRACE_ON)
> > >                     generate_sample = true;
> > >
> > > +           /* Generate sample for tracing off packet */
> > > +           if (etmq->prev_packet->sample_type == CS_ETM_TRACE_OFF)
> > > +                   generate_sample = true;
> > > +
> > >             /* Generate sample for branch taken packet */
> > >             if (etmq->prev_packet->sample_type == CS_ETM_RANGE &&
> > >                 etmq->prev_packet->last_instr_taken_branch)
> > > @@ -1085,6 +1091,7 @@ static int cs_etm__run_decoder(struct cs_etm_queue *etmq)
> > >                                     cs_etm__sample(etmq);
> > >                                     break;
> > >                             case CS_ETM_TRACE_ON:
> > > +                           case CS_ETM_TRACE_OFF:
> > >                                     /*
> > >                                      * Discontinuity in trace, flush
> > >                                      * previous branch stack
> > > --
> > > 2.7.4
> > >
Leo Yan Dec. 6, 2018, 5:45 a.m. UTC | #4
On Wed, Dec 05, 2018 at 10:48:45AM -0700, Mathieu Poirier wrote:

[...]

> > So I think there still have some difference between TRACE_ON and
> > NO_SYNC packets, TRACE_ON packet indicates the start of trace and it's
> > also possible caused by tracing discontinuity; NO_SYNC packets usually
> > caused by an unsynchronised state.  But both of them presents
> > discontinuity in perf trace data.
> >
> > I prefer to use two different packet types to present them, this can
> > let the code to be more readable and easier to be maintained later.
> 
> Absolutely.  Make sure to get to the bottom of the story with Mike
> and/or Robert before sending your next patchset.

Sure, will sync with Mike/Rob.

Thanks,
Leo Yan

Patch
diff mbox series

diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
index 5efb616..9d52727 100644
--- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
+++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
@@ -369,6 +369,14 @@  cs_etm_decoder__buffer_range(struct cs_etm_decoder *decoder,
 }
 
 static ocsd_datapath_resp_t
+cs_etm_decoder__buffer_trace_off(struct cs_etm_decoder *decoder,
+				 const uint8_t trace_chan_id)
+{
+	return cs_etm_decoder__buffer_packet(decoder, trace_chan_id,
+					     CS_ETM_TRACE_OFF);
+}
+
+static ocsd_datapath_resp_t
 cs_etm_decoder__buffer_trace_on(struct cs_etm_decoder *decoder,
 				const uint8_t trace_chan_id)
 {
@@ -389,6 +397,8 @@  static ocsd_datapath_resp_t cs_etm_decoder__gen_trace_elem_printer(
 	case OCSD_GEN_TRC_ELEM_UNKNOWN:
 		break;
 	case OCSD_GEN_TRC_ELEM_NO_SYNC:
+		resp = cs_etm_decoder__buffer_trace_off(decoder,
+							trace_chan_id);
 		decoder->trace_on = false;
 		break;
 	case OCSD_GEN_TRC_ELEM_TRACE_ON:
diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
index 9351bd1..a38c97c 100644
--- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
+++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
@@ -23,9 +23,10 @@  struct cs_etm_buffer {
 };
 
 enum cs_etm_sample_type {
-	CS_ETM_EMPTY = 0,
-	CS_ETM_RANGE = 1 << 0,
-	CS_ETM_TRACE_ON = 1 << 1,
+	CS_ETM_EMPTY		= 0,
+	CS_ETM_RANGE		= 1 << 0,
+	CS_ETM_TRACE_ON		= 1 << 1,
+	CS_ETM_TRACE_OFF	= 1 << 2,
 };
 
 enum cs_etm_isa {
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index f4fa877..2a0cef9 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -517,8 +517,9 @@  static inline int cs_etm__t32_instr_size(struct cs_etm_queue *etmq,
 
 static inline u64 cs_etm__first_executed_instr(struct cs_etm_packet *packet)
 {
-	/* Returns 0 for the CS_ETM_TRACE_ON packet */
-	if (packet->sample_type == CS_ETM_TRACE_ON)
+	/* Returns 0 for TRACE_ON and TRACE_OFF packets */
+	if (packet->sample_type == CS_ETM_TRACE_ON ||
+	    packet->sample_type == CS_ETM_TRACE_OFF)
 		return 0;
 
 	return packet->start_addr;
@@ -527,8 +528,9 @@  static inline u64 cs_etm__first_executed_instr(struct cs_etm_packet *packet)
 static inline
 u64 cs_etm__last_executed_instr(const struct cs_etm_packet *packet)
 {
-	/* Returns 0 for the CS_ETM_TRACE_ON packet */
-	if (packet->sample_type == CS_ETM_TRACE_ON)
+	/* Returns 0 for TRACE_ON and TRACE_OFF packets */
+	if (packet->sample_type == CS_ETM_TRACE_ON ||
+	    packet->sample_type == CS_ETM_TRACE_OFF)
 		return 0;
 
 	return packet->end_addr - packet->last_instr_size;
@@ -930,6 +932,10 @@  static int cs_etm__sample(struct cs_etm_queue *etmq)
 		if (etmq->prev_packet->sample_type == CS_ETM_TRACE_ON)
 			generate_sample = true;
 
+		/* Generate sample for tracing off packet */
+		if (etmq->prev_packet->sample_type == CS_ETM_TRACE_OFF)
+			generate_sample = true;
+
 		/* Generate sample for branch taken packet */
 		if (etmq->prev_packet->sample_type == CS_ETM_RANGE &&
 		    etmq->prev_packet->last_instr_taken_branch)
@@ -1085,6 +1091,7 @@  static int cs_etm__run_decoder(struct cs_etm_queue *etmq)
 					cs_etm__sample(etmq);
 					break;
 				case CS_ETM_TRACE_ON:
+				case CS_ETM_TRACE_OFF:
 					/*
 					 * Discontinuity in trace, flush
 					 * previous branch stack