From: German Gomez <german.gomez@arm.com>

Date: Tue, 18 Jan 2022 14:40:54 +0000

Subject: perf evsel: Override attr->sample_period for non-libpfm4 events

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Git-commit: 3606c0e1a1050d397ad759a62607e419fd8b0ccb

Patch-mainline: v5.17-rc1

References: git-fixes

X-Info: adjust for context, no eb39bf325631f9ae185abd16281079b7b9858737

​

​

A previous patch preventing "attr->sample_period" values from being

overridden in pfm events changed a related behaviour in arm-spe.

​

Before said patch:

​

  perf record -c 10000 -e arm_spe_0// -- sleep 1

​

Would yield an SPE event with period=10000. After the patch, the period

in "-c 10000" was being ignored because the arm-spe code initializes

sample_period to a non-zero value.

​

This patch restores the previous behaviour for non-libpfm4 events.

​

Fixes: ae5dcc8abe31 (“perf record: Prevent override of attr->sample_period for libpfm4 events”)

Reported-by: Chase Conklin <chase.conklin@arm.com>

Signed-off-by: German Gomez <german.gomez@arm.com>

Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>

Cc: Ian Rogers <irogers@google.com>

Cc: Jiri Olsa <jolsa@redhat.com>

Cc: John Fastabend <john.fastabend@gmail.com>

Cc: KP Singh <kpsingh@kernel.org>

Cc: Mark Rutland <mark.rutland@arm.com>

Cc: Martin KaFai Lau <kafai@fb.com>

Cc: Namhyung Kim <namhyung@kernel.org>

Cc: Song Liu <songliubraving@fb.com>

Cc: Stephane Eranian <eranian@google.com>

Cc: Yonghong Song <yhs@fb.com>

Cc: bpf@vger.kernel.org

Cc: netdev@vger.kernel.org

Link: http://lore.kernel.org/lkml/20220118144054.2541-1-german.gomez@arm.com

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Signed-off-by: Tony Jones <tonyj@suse.de>

---

 tools/perf/util/evsel.c | 25 +++++++++++++++++--------

 1 file changed, 17 insertions(+), 8 deletions(-)

​

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c

index fb0a2debf015..22d3267ce294 100644

--- a/tools/perf/util/evsel.c

+++ b/tools/perf/util/evsel.c

@@ -1064,6 +1064,17 @@ void __weak arch_evsel__fixup_new_cycles(struct perf_event_attr *attr __maybe_un

    evsel__set_sample_bit(evsel, WEIGHT);

 }

+static void evsel__set_default_freq_period(struct record_opts *opts,

+                      struct perf_event_attr *attr)

+{

+   if (opts->freq) {

+       attr->freq = 1;

+       attr->sample_freq = opts->freq;

+   } else {

+       attr->sample_period = opts->default_interval;

+   }

+}

+

 /*

  * The enable_on_exec/disabled value strategy:

  *

@@ -1130,14 +1141,12 @@ void evsel__config(struct evsel *evsel, struct record_opts *opts,

     * We default some events to have a default interval. But keep

     * it a weak assumption overridable by the user.

     */

-   if (!attr->sample_period) {

-       if (opts->freq) {

-           attr->freq      = 1;

-           attr->sample_freq   = opts->freq;

-       } else {

-           attr->sample_period = opts->default_interval;

-       }

-   }

+   if ((evsel->is_libpfm_event && !attr->sample_period) ||

+       (!evsel->is_libpfm_event && (!attr->sample_period ||

+                    opts->user_freq != UINT_MAX ||

+                    opts->user_interval != ULLONG_MAX)))

+       evsel__set_default_freq_period(opts, attr);

+

    /*

     * If attr->freq was set (here or earlier), ask for period

     * to be sampled.

​

​