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Commit 3d918fb1 authored by Adrian Hunter's avatar Adrian Hunter Committed by Arnaldo Carvalho de Melo
Browse files

perf intel-pt: Fix occasional decoding errors when tracing system-wide 



In order to successfully decode Intel PT traces, context switch events
are needed from the moment the trace starts. Currently that is ensured
by using the 'immediate' flag which enables the switch event when it is
opened.

However, since commit 86c27869 ("perf intel-pt: Add support for
PERF_RECORD_SWITCH") that might not always happen. When tracing
system-wide the context switch event is added to the tracking event
which was not set as 'immediate'. Change that so it is.

Signed-off-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org # v4.4+
Fixes: 86c27869 ("perf intel-pt: Add support for PERF_RECORD_SWITCH")
Link: http://lkml.kernel.org/r/1471245784-22580-1-git-send-email-adrian.hunter@intel.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 9f315690

tools/perf/arch/x86/util/intel-pt.c

+5 −1
Original line number Diff line number Diff line
@@ -501,7 +501,7 @@ static int intel_pt_recording_options(struct auxtrace_record *itr, 
	struct intel_pt_recording *ptr =

			container_of(itr, struct intel_pt_recording, itr);

	struct perf_pmu *intel_pt_pmu = ptr->intel_pt_pmu;

	bool have_timing_info;

	bool have_timing_info, need_immediate = false;

	struct perf_evsel *evsel, *intel_pt_evsel = NULL;

	const struct cpu_map *cpus = evlist->cpus;

	bool privileged = geteuid() == 0 || perf_event_paranoid() < 0;
@@ -655,6 +655,7 @@ static int intel_pt_recording_options(struct auxtrace_record *itr, 
				ptr->have_sched_switch = 3;

			} else {

				opts->record_switch_events = true;

				need_immediate = true;

				if (cpu_wide)

					ptr->have_sched_switch = 3;

				else
@@ -700,6 +701,9 @@ static int intel_pt_recording_options(struct auxtrace_record *itr, 
		tracking_evsel->attr.freq = 0;

		tracking_evsel->attr.sample_period = 1;



		if (need_immediate)

			tracking_evsel->immediate = true;



		/* In per-cpu case, always need the time of mmap events etc */

		if (!cpu_map__empty(cpus)) {

			perf_evsel__set_sample_bit(tracking_evsel, TIME);