From f1410028c762893daf353765112cf6797e4442fa Mon Sep 17 00:00:00 2001 From: Leo Yan Date: Wed, 19 Feb 2020 10:18:08 +0800 Subject: [PATCH] perf cs-etm: Continuously record last branch Every time synthesize instruction sample, the last branch recording will be reset. This is fine if the instruction period is big enough, for example if use the option '--itrace=i100000', the last branch array is reset for every sample with 100000 instructions per period; before generate the next instruction sample, there has the sufficient packets coming to fill the last branch array. On the other hand, if set a very small period, the packets will be significantly reduced between two continuous instruction samples, thus the last branch array is almost empty for new instruction sample by frequently resetting. To allow the last branches to work properly for any instruction periods, this patch avoids to reset the last branch for every instruction sample and only reset it when flush the trace data. The last branches will be reset only for two cases, one is for trace starting, another case is for discontinuous trace; other cases can keep recording last branches for continuous instruction samples. Signed-off-by: Leo Yan Reviewed-by: Mathieu Poirier Reviewed-by: Mike Leach Cc: Alexander Shishkin Cc: Jiri Olsa Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Robert Walker Cc: Suzuki Poulouse Cc: coresight ml Cc: linux-arm-kernel@lists.infradead.org Link: http://lore.kernel.org/lkml/20200219021811.20067-3-leo.yan@linaro.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/cs-etm.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c index 294b09cfb034..2c4156c5ed09 100644 --- a/tools/perf/util/cs-etm.c +++ b/tools/perf/util/cs-etm.c @@ -1170,9 +1170,6 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq, "CS ETM Trace: failed to deliver instruction event, error %d\n", ret); - if (etm->synth_opts.last_branch) - cs_etm__reset_last_branch_rb(tidq); - return ret; } @@ -1487,6 +1484,10 @@ static int cs_etm__flush(struct cs_etm_queue *etmq, swap_packet: cs_etm__packet_swap(etm, tidq); + /* Reset last branches after flush the trace */ + if (etm->synth_opts.last_branch) + cs_etm__reset_last_branch_rb(tidq); + return err; }