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From:   Leo Yan <leo.yan@linaro.org>
To:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        John Garry <john.garry@huawei.com>,
        Will Deacon <will@kernel.org>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        James Clark <james.clark@arm.com>, Al Grant <Al.Grant@arm.com>,
        linux-arm-kernel@lists.infradead.org,
        linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Leo Yan <leo.yan@linaro.org>
Subject: [PATCH v2 2/4] perf arm-spe: Correct sample flags for dummy event
Date:   Wed, 19 May 2021 12:15:44 +0800
Message-Id: <20210519041546.1574961-3-leo.yan@linaro.org>
In-Reply-To: <20210519041546.1574961-1-leo.yan@linaro.org>
References: <20210519041546.1574961-1-leo.yan@linaro.org>
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The dummy event is mainly used for mmap, the TIME sample is only needed
for per-cpu case so that the perf tool can rely on the correct timing
for parsing symbols.  And the CPU sample is useless for mmap.

The BRANCH_STACK sample bit will be always reset for the dummy event in
the function evsel__config(), so don't need to repeatedly reset it for
Arm SPE specific.

So this patch only enables TIME sample for per-cpu mmap.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: James Clark <james.clark@arm.com>
Tested-by: James Clark <james.clark@arm.com>
---
 tools/perf/arch/arm64/util/arm-spe.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/perf/arch/arm64/util/arm-spe.c b/tools/perf/arch/arm64/util/arm-spe.c
index 902e73a64184..4c916626c203 100644
--- a/tools/perf/arch/arm64/util/arm-spe.c
+++ b/tools/perf/arch/arm64/util/arm-spe.c
@@ -135,9 +135,10 @@ static int arm_spe_recording_options(struct auxtrace_record *itr,
 
 	tracking_evsel->core.attr.freq = 0;
 	tracking_evsel->core.attr.sample_period = 1;
-	evsel__set_sample_bit(tracking_evsel, TIME);
-	evsel__set_sample_bit(tracking_evsel, CPU);
-	evsel__reset_sample_bit(tracking_evsel, BRANCH_STACK);
+
+	/* In per-cpu case, always need the time of mmap events etc */
+	if (!perf_cpu_map__empty(cpus))
+		evsel__set_sample_bit(tracking_evsel, TIME);
 
 	return 0;
 }
-- 
2.25.1