Messages in this thread Patch in this message | | | From | kan.liang@linux ... | Subject | [PATCH V3 3/5] perf/x86/intel/ds: introduce read function for large pebs | Date | Mon, 29 Jan 2018 08:29:31 -0800 |
| |
From: Kan Liang <kan.liang@linux.intel.com>
When the PEBS interrupt threshold is larger than one, there is no way to get exact auto-reload times and value, which needed for event update unless flush the PEBS buffer.
Introduce intel_pmu_large_pebs_read() to drain the PEBS buffer in event read when large PEBS is enabled. To prevent the race, the drain_pebs() only be called when the PMU is disabled.
Unconditionally call x86_perf_event_update() for large pebs. - It is easily to call pmu::read() twice in a short period. There could be no samples in the PEBS buffer. x86_perf_event_update() is needed to update the count. - There is no harmful to call x86_perf_event_update() for other cases. - It's safe. Don't need to worry about the auto-reload. Because the PMU is disabled.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com> --- arch/x86/events/intel/ds.c | 16 ++++++++++++++++ arch/x86/events/perf_event.h | 2 ++ 2 files changed, 18 insertions(+)
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c index 6533426..1c11fa2 100644 --- a/arch/x86/events/intel/ds.c +++ b/arch/x86/events/intel/ds.c @@ -1303,6 +1303,22 @@ get_next_pebs_record_by_bit(void *base, void *top, int bit) return NULL; } +int intel_pmu_large_pebs_read(struct perf_event *event) +{ + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); + + /* Check if the event has large pebs */ + if (!pebs_needs_sched_cb(cpuc)) + return 0; + + perf_pmu_disable(event->pmu); + intel_pmu_drain_pebs_buffer(); + x86_perf_event_update(event); + perf_pmu_enable(event->pmu); + + return 1; +} + /* * Specific intel_pmu_save_and_restart() for auto-reload. * It only be called from drain_pebs(). diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h index 805400b..7d3cd32 100644 --- a/arch/x86/events/perf_event.h +++ b/arch/x86/events/perf_event.h @@ -923,6 +923,8 @@ void intel_pmu_pebs_disable_all(void); void intel_pmu_pebs_sched_task(struct perf_event_context *ctx, bool sched_in); +int intel_pmu_large_pebs_read(struct perf_event *event); + void intel_ds_init(void); void intel_pmu_lbr_sched_task(struct perf_event_context *ctx, bool sched_in); -- 2.7.4
| |