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From:   German Gomez <german.gomez@arm.com>
To:     linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
        acme@kernel.org
Cc:     German Gomez <german.gomez@arm.com>,
        John Garry <john.garry@huawei.com>,
        Will Deacon <will@kernel.org>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Leo Yan <leo.yan@linaro.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        linux-arm-kernel@lists.infradead.org
Subject: [PATCH] perf arm-spe: Use advertised caps/min_interval as default sample_period
Date:   Mon, 21 Feb 2022 17:10:42 +0000
Message-Id: <20220221171042.58460-1-german.gomez@arm.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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@arm.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