niansa-misc/linux
1
0
Fork 0
mirror of synced 2025-03-06 20:59:54 +01:00
Code Issues Projects Releases Packages Wiki Activity

perf/x86: Fix low freqency setting issue

Browse source 
Perf doesn't work at low frequencies:

  $ perf record -e cpu_core/instructions/ppp -F 120
  Error:
  The sys_perf_event_open() syscall returned with 22 (Invalid argument)
  for event (cpu_core/instructions/ppp).
  "dmesg | grep -i perf" may provide additional information.

The limit_period() check avoids a low sampling period on a counter. It
doesn't intend to limit the frequency.

The check in the x86_pmu_hw_config() should be limited to non-freq mode.
The attr.sample_period and attr.sample_freq are union. The
attr.sample_period should not be used to indicate the frequency mode.

Fixes: c46e665f03 ("perf/x86: Add INST_RETIRED.ALL workarounds")
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250117151913.3043942-1-kan.liang@linux.intel.com
Closes: https://lore.kernel.org/lkml/20250115154949.3147-1-ravi.bangoria@amd.com/
This commit is contained in:
Kan Liang 2025-01-17 07:19:11 -08:00 • committed by Ingo Molnar
parent bddf10d26e
commit 88ec7eedbb
1 changed files with 1 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
arch/x86/events/core.c
View file

@ -628,7 +628,7 @@ int x86_pmu_hw_config(struct perf_event *event)
if (event->attr.type == event->pmu->type)
event->hw.config |= x86_pmu_get_event_config(event);
if (event->attr.sample_period && x86_pmu.limit_period) {
if (!event->attr.freq && x86_pmu.limit_period) {
s64 left = event->attr.sample_period;
x86_pmu.limit_period(event, &left);
if (left > event->attr.sample_period)