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Luo GengkunIngo Molnar
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perf/x86: Fix non-sampling (counting) events on certain x86 platforms
Perf doesn't work at perf stat for hardware events on certain x86 platforms: $perf stat -- sleep 1 Performance counter stats for 'sleep 1': 16.44 msec task-clock # 0.016 CPUs utilized 2 context-switches # 121.691 /sec 0 cpu-migrations # 0.000 /sec 54 page-faults # 3.286 K/sec <not supported> cycles <not supported> instructions <not supported> branches <not supported> branch-misses The reason is that the check in x86_pmu_hw_config() for sampling events is unexpectedly applied to counting events as well. It should only impact x86 platforms with limit_period used for non-PEBS events. For Intel platforms, it should only impact some older platforms, e.g., HSW, BDW and NHM. Fixes: 88ec7ee ("perf/x86: Fix low freqency setting issue") Signed-off-by: Luo Gengkun <luogengkun@huaweicloud.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Kan Liang <kan.liang@linux.intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi Bangoria <ravi.bangoria@amd.com> Link: https://lore.kernel.org/r/20250423064724.3716211-1-luogengkun@huaweicloud.com
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arch/x86/events/core.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -629,7 +629,7 @@ int x86_pmu_hw_config(struct perf_event *event)
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if (event->attr.type == event->pmu->type)
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event->hw.config |= x86_pmu_get_event_config(event);
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if (!event->attr.freq && x86_pmu.limit_period) {
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if (is_sampling_event(event) && !event->attr.freq && x86_pmu.limit_period) {
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s64 left = event->attr.sample_period;
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x86_pmu.limit_period(event, &left);
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if (left > event->attr.sample_period)

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