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Message-ID: <c2b960eb-a25e-7ce7-ee4b-2be557d8a213@arm.com> Date: Mon, 17 Jan 2022 09:59:12 +0000 From: James Clark <james.clark@....com> To: German Gomez <german.gomez@....com>, linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org Cc: Chase Conklin <chase.conklin@....com>, Mark Rutland <mark.rutland@....com>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung@...nel.org>, Martin KaFai Lau <kafai@...com>, Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>, John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>, Ian Rogers <irogers@...gle.com>, Arnaldo Carvalho de Melo <acme@...hat.com>, Stephane Eranian <eranian@...gle.com>, netdev@...r.kernel.org, bpf@...r.kernel.org, "acme@...nel.org" <acme@...nel.org> Subject: Re: [PATCH] perf record/arm-spe: Override attr->sample_period for non-libpfm4 events On 14/01/2022 21:21, German Gomez wrote: > A previous commit preventing attr->sample_period values from being > overridden in pfm events changed a related behaviour in arm_spe. > > Before this patch: > perf record -c 10000 -e arm_spe_0// -- sleep 1 > > Would not yield an SPE event with period=10000, because the arm-spe code Just to clarify, this seems like it should say "Would yield", not "Would not yield", as in it was previously working? > initializes sample_period to a non-0 value, so the "-c 10000" is ignored. > > This patch restores the previous behaviour for non-libpfm4 events. > > Reported-by: Chase Conklin <chase.conklin@....com> > Fixes: ae5dcc8abe31 (“perf record: Prevent override of attr->sample_period for libpfm4 events”) > Signed-off-by: German Gomez <german.gomez@....com> > --- > 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 a59fb2ecb84e..86ab038f020f 100644 > --- a/tools/perf/util/evsel.c > +++ b/tools/perf/util/evsel.c > @@ -1065,6 +1065,17 @@ 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: > * > @@ -1131,14 +1142,12 @@ 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. >
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