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Subject[PATCH 41/85] perf cs-etm: Add handling of switch-CPU-wide events
Date
From: Mathieu Poirier <mathieu.poirier@linaro.org>

Add handling of SWITCH-CPU-WIDE events in order to add the tid/pid of
the incoming process to the perf tools machine infrastructure. This
information is later retrieved when a contextID packet is found in the
trace stream.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Tested-by: Leo Yan <leo.yan@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20190524173508.29044-6-mathieu.poirier@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/cs-etm.c | 38 ++++++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 0742c50fce46..5322dcaaf654 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1680,6 +1680,42 @@ static int cs_etm__process_itrace_start(struct cs_etm_auxtrace *etm,
return 0;
}

+static int cs_etm__process_switch_cpu_wide(struct cs_etm_auxtrace *etm,
+ union perf_event *event)
+{
+ struct thread *th;
+ bool out = event->header.misc & PERF_RECORD_MISC_SWITCH_OUT;
+
+ /*
+ * Context switch in per-thread mode are irrelevant since perf
+ * will start/stop tracing as the process is scheduled.
+ */
+ if (etm->timeless_decoding)
+ return 0;
+
+ /*
+ * SWITCH_IN events carry the next process to be switched out while
+ * SWITCH_OUT events carry the process to be switched in. As such
+ * we don't care about IN events.
+ */
+ if (!out)
+ return 0;
+
+ /*
+ * Add the tid/pid to the log so that we can get a match when
+ * we get a contextID from the decoder.
+ */
+ th = machine__findnew_thread(etm->machine,
+ event->context_switch.next_prev_pid,
+ event->context_switch.next_prev_tid);
+ if (!th)
+ return -ENOMEM;
+
+ thread__put(th);
+
+ return 0;
+}
+
static int cs_etm__process_event(struct perf_session *session,
union perf_event *event,
struct perf_sample *sample,
@@ -1719,6 +1755,8 @@ static int cs_etm__process_event(struct perf_session *session,

if (event->header.type == PERF_RECORD_ITRACE_START)
return cs_etm__process_itrace_start(etm, event);
+ else if (event->header.type == PERF_RECORD_SWITCH_CPU_WIDE)
+ return cs_etm__process_switch_cpu_wide(etm, event);

return 0;
}
--
2.20.1
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