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| author | Peter Zijlstra (Intel) <peterz@infradead.org> | 2025-01-21 07:23:02 -0800 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2025-02-05 10:29:45 +0100 |
| commit | 8ce939a0fa194939cc1f92dbd8bc1a7806e7d40a (patch) | |
| tree | 68046b67ba49a0feb3c687e5831c9e39b263b4e3 /kernel/events/ring_buffer.c | |
| parent | perf/x86/intel: Avoid disable PMU if !cpuc->enabled in sample read (diff) | |
| download | linux-8ce939a0fa194939cc1f92dbd8bc1a7806e7d40a.tar.gz linux-8ce939a0fa194939cc1f92dbd8bc1a7806e7d40a.zip | |
perf: Avoid the read if the count is already updated
The event may have been updated in the PMU-specific implementation,
e.g., Intel PEBS counters snapshotting. The common code should not
read and overwrite the value.
The PERF_SAMPLE_READ in the data->sample_type can be used to detect
whether the PMU-specific value is available. If yes, avoid the
pmu->read() in the common code. Add a new flag, skip_read, to track the
case.
Factor out a perf_pmu_read() to clean up the code.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250121152303.3128733-3-kan.liang@linux.intel.com
Diffstat (limited to 'kernel/events/ring_buffer.c')
| -rw-r--r-- | kernel/events/ring_buffer.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 180509132d4b..59a52b1a1f78 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -185,6 +185,7 @@ __perf_output_begin(struct perf_output_handle *handle, handle->rb = rb; handle->event = event; + handle->flags = 0; have_lost = local_read(&rb->lost); if (unlikely(have_lost)) { |