Hi Arnaldo, On Thu, Dec 13, 2018 at 09:41:54AM -0300, Arnaldo Carvalho de Melo wrote: > Em Thu, Dec 13, 2018 at 09:38:54AM -0300, Arnaldo Carvalho de Melo escreveu: > > Em Tue, Dec 11, 2018 at 03:38:26PM +0800, Leo Yan escreveu: > > > CoreSight tracer driver might insert barrier packet between different > > > buffers, thus the decoder can spot the boundaries based on the barrier > > > packet; the decoder is possible to hit a barrier packet and emit a > > > NO_SYNC element, then the decoder will find a periodic synchronisation > > > point inside that next trace block that starts trace again but does not > > > have the TRACE_ON element as indicator - usually because this block of > > > trace has wrapped the buffer so we have lost the original point that > > > trace was enabled. > > > > > > In upper case, it results in the trace stream only inserts the > > > OCSD_GEN_TRC_ELEM_NO_SYNC element in the middle of tracing stream, but > > > we don't handle NO_SYNC element properly and at the end users miss to > > > see the info for trace discontinuity. > > > > > > "In upper case"? Maybe: > > > > In the former case it causes the insertion of a OCSD_GEN_TRC_ELEM_NO_SYNC > > in the middle of the the tracing stream, but as we were npt handling the > > NO_SYNC element properly which ends up making users miss the > > discontinuity indication"? > > > > Though OCSD_GEN_TRC_ELEM_NO_SYNC is different from CS_ETM_TRACE_ON when > > > output from the decoder, but both of them indicate the trace data is > > > > can we remove the "but" and "of them" (redundant) above? > > > > > discontinuous; this patch treats OCSD_GEN_TRC_ELEM_NO_SYNC as trace > > a > > > discontinuity and generates CS_ETM_DISCONTINUITY packet for it, so > > > cs-etm can handle discontinuity for this case, finally it saves the last > > it (way too many "discontinuity") > > > trace data for previous trace block and restart samples for new block. > > I've tentatively done those changes (and a few more) in my local branch, > resulting in the wording below, plese let me know if you are ok with it:
Very appreciate your helping. Please see some minor typos in below commit: > commit 148068b45fe2e93b19c06cfc1140ea12ca72eb59 > Author: Leo Yan <leo....@linaro.org> > Date: Tue Dec 11 15:38:26 2018 +0800 > > perf cs-etm: Treat NO_SYNC element as trace discontinuity > > The CoreSight tracer driver might insert a barrier packets between packet > different buffers, thus the decoder can spot the boundaries based on the > barrier packet; it is possible for the decoder to hit a barrier packet > and emit a NO_SYNC element, then the decoder will find a periodic > synchronisation point inside that next trace block that starts the trace > again but does not have the TRACE_ON element as indicator - usually > because this trace block has wrapped the buffer so we have lost the > original point when the trace was enabled. > > In the first case it causes the insertion of a OCSD_GEN_TRC_ELEM_NO_SYNC former > in the middle of the the tracing stream, but as we were npt handling the not > NO_SYNC element properly which ends up making users miss the > discontinuity indication"? s/?/. Thanks a lot for helping. If you prefer me to resend the patch set, also let me know. > Though OCSD_GEN_TRC_ELEM_NO_SYNC is different from CS_ETM_TRACE_ON when > output from the decoder, both indicate that the trace data is > discontinuous; this patch treats OCSD_GEN_TRC_ELEM_NO_SYNC as a trace > discontinuity and generates a CS_ETM_DISCONTINUITY packet for it, so > cs-etm can handle the discontinuity for this case, finally it saves the > last trace data for the previous trace block and restart samples for the > new block. > > Signed-off-by: Leo Yan <leo....@linaro.org> > Reviewed-by: Mathieu Poirier <mathieu.poir...@linaro.org> > Cc: Alexander Shishkin <alexander.shish...@linux.intel.com> > Cc: Jiri Olsa <jo...@redhat.com> > Cc: Mike Leach <mike.le...@linaro.org> > Cc: Namhyung Kim <namhy...@kernel.org> > Cc: Robert Walker <robert.wal...@arm.com> > Cc: coresight ml <coresi...@lists.linaro.org> > Cc: linux-arm-ker...@lists.infradead.org > Link: > http://lkml.kernel.org/r/1544513908-16805-7-git-send-email-leo....@linaro.org > Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com> > > 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 1039f364f4cc..bee026e76a4c 100644 > --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c > +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c > @@ -410,7 +410,6 @@ 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: > - break; > case OCSD_GEN_TRC_ELEM_TRACE_ON: > resp = cs_etm_decoder__buffer_discontinuity(decoder, > trace_chan_id); > >