* [PATCH 5.16 0943/1039] perf evsel: Override attr->sample_period for non-libpfm4 events
[not found] <20220124184125.121143506@linuxfoundation.org>
@ 2022-01-24 18:45 ` Greg Kroah-Hartman
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From: Greg Kroah-Hartman @ 2022-01-24 18:45 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Chase Conklin, German Gomez,
Alexander Shishkin, Ian Rogers, Jiri Olsa, John Fastabend,
KP Singh, Mark Rutland, Martin KaFai Lau, Namhyung Kim, Song Liu,
Stephane Eranian, Yonghong Song, bpf, netdev,
Arnaldo Carvalho de Melo
From: German Gomez <german.gomez@arm•com>
commit 3606c0e1a1050d397ad759a62607e419fd8b0ccb upstream.
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: Greg Kroah-Hartman <gregkh@linuxfoundation•org>
---
tools/perf/util/evsel.c | 25 +++++++++++++++++--------
1 file changed, 17 insertions(+), 8 deletions(-)
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1064,6 +1064,17 @@ void __weak arch_evsel__fixup_new_cycles
{
}
+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,
* 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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