Commit 3606c0e1 authored Jan 18, 2022 by German Gomez Committed by Arnaldo Carvalho de Melo Jan 22, 2022

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



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: ae5dcc8a (“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>

parent 24ead7c2

tools/perf/util/evsel.c

+17 −8

Original line number	Diff line number	Diff line
		@@ -1064,6 +1064,17 @@ void __weak arch_evsel__fixup_new_cycles(struct perf_event_attr *attr __maybe_un
		{
		}

		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.