linux-kernel - [PATCH] perf arm-spe: Use advertised caps/min_interval as default sample

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Date:   Mon, 21 Feb 2022 17:10:42 +0000
From:   German Gomez <german.gomez@....com>
To:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        acme@...nel.org
Cc:     German Gomez <german.gomez@....com>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH] perf arm-spe: Use advertised caps/min_interval as default sample_period

When recording SPE traces, the default sample_period is currently being
set to 1 in the perf_event_attr fields, instead of the value advertised
in '/sys/devices/arm_spe_0/caps/min_interval':

Before:

$ perf record -e arm_spe// -vv -- sleep 1
[...]
  { sample_period, sample_freq }   1
[...]

Use the value from the above sysfs location as a more sensible default
(it was already being read, but the value not being used)

After:

$ perf record -e arm_spe// -vv -- sleep 1
[...]
  { sample_period, sample_freq }   1024
[...]

Signed-off-by: German Gomez <german.gomez@....com>
---
 tools/perf/arch/arm64/util/arm-spe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/arch/arm64/util/arm-spe.c b/tools/perf/arch/arm64/util/arm-spe.c
index 2100d46cc..5860bbaea 100644
--- a/tools/perf/arch/arm64/util/arm-spe.c
+++ b/tools/perf/arch/arm64/util/arm-spe.c
@@ -158,7 +158,7 @@ static int arm_spe_recording_options(struct auxtrace_record *itr,
 				return -EINVAL;
 			}
 			evsel->core.attr.freq = 0;
-			evsel->core.attr.sample_period = 1;
+			evsel->core.attr.sample_period = arm_spe_pmu->default_config->sample_period;
 			arm_spe_evsel = evsel;
 			opts->full_auxtrace = true;
 		}
-- 
2.25.1