diff options
| author | Uros Bizjak <ubizjak@gmail.com> | 2023-07-03 17:00:59 +0200 |
|---|---|---|
| committer | Alex Deucher <alexander.deucher@amd.com> | 2023-08-09 18:08:51 -0400 |
| commit | 9e761bff03e137fca0c41fd3bcc3e88167d59dc1 (patch) | |
| tree | 3022d4c81133a842ca8ef7838240a0ff3d4d61bb | |
| parent | 59070fd9ccea58c3363d39f69c25fa98c71eb02f (diff) | |
drm/amdgpu: Use local64_try_cmpxchg in amdgpu_perf_read
Use local64_try_cmpxchg instead of local64_cmpxchg (*ptr, old, new) == old
in amdgpu_perf_read. x86 CMPXCHG instruction returns success in ZF flag,
so this change saves a compare after cmpxchg (and related move instruction
in front of cmpxchg).
Also, try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg
fails. There is no need to re-read the value in the loop.
No functional change intended.
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
Cc: David Airlie <airlied@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
| -rw-r--r-- | drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c index 71ee361d0972..6e91ea1de5aa 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pmu.c @@ -276,9 +276,8 @@ static void amdgpu_perf_read(struct perf_event *event) (!pe->adev->df.funcs->pmc_get_count)) return; + prev = local64_read(&hwc->prev_count); do { - prev = local64_read(&hwc->prev_count); - switch (hwc->config_base) { case AMDGPU_PMU_EVENT_CONFIG_TYPE_DF: case AMDGPU_PMU_EVENT_CONFIG_TYPE_XGMI: @@ -289,7 +288,7 @@ static void amdgpu_perf_read(struct perf_event *event) count = 0; break; } - } while (local64_cmpxchg(&hwc->prev_count, prev, count) != prev); + } while (!local64_try_cmpxchg(&hwc->prev_count, &prev, count)); local64_add(count - prev, &event->count); } |