[v1,3/5] perf cs-etm: Support for NO_SYNC packet

Message ID 1541912383-19915-4-git-send-email-leo.yan@linaro.org
State New
Headers show
Series
  • perf cs-etm: Correct packets handling
Related show

Commit Message

Leo Yan Nov. 11, 2018, 4:59 a.m.
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(-)

-- 
2.7.4

Comments

Mathieu Poirier Nov. 19, 2018, 6:27 p.m. | #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. | #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. | #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. | #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 --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