Messages in this thread | | | Date | Mon, 19 Nov 2018 11:27:59 -0700 | From | Mathieu Poirier <> | Subject | Re: [PATCH v1 3/5] perf cs-etm: Support for NO_SYNC packet |
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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 >
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