perf/x86/intel/ds: Introduce ->read() function for auto-reload events and flush the...

There is no way to get exact auto-reload times and values which are needed
for event updates unless we flush the PEBS buffer.

Introduce intel_pmu_auto_reload_read() to drain the PEBS buffer for
auto reload event. To prevent races with the hardware, we can only
call drain_pebs() when the PMU is disabled.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: acme@kernel.org
Link: http://lkml.kernel.org/r/1518474035-21006-4-git-send-email-kan.liang@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index f39a4df3a7bdf6088898902eaf236d685054a557..73844025adaf2f1c3fc855b2330b9620a3b2759e 100644 (file)
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1306,6 +1306,15 @@ get_next_pebs_record_by_bit(void *base, void *top, int bit)
        return NULL;
 }
 
+void intel_pmu_auto_reload_read(struct perf_event *event)
+{
+       WARN_ON(!(event->hw.flags & PERF_X86_EVENT_AUTO_RELOAD));
+
+       perf_pmu_disable(event->pmu);
+       intel_pmu_drain_pebs_buffer();
+       perf_pmu_enable(event->pmu);
+}
+
 /*
  * Special variant of intel_pmu_save_and_restart() for auto-reload.
  */

diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index d445f00269899f5288e6d0945c6a2a21392e2824..91643472f385fa8ec9fe735b3931a5767ff41db2 100644 (file)
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -924,6 +924,8 @@ void intel_pmu_pebs_disable_all(void);
 
 void intel_pmu_pebs_sched_task(struct perf_event_context *ctx, bool sched_in);
 
+void intel_pmu_auto_reload_read(struct perf_event *event);
+
 void intel_ds_init(void);
 
 void intel_pmu_lbr_sched_task(struct perf_event_context *ctx, bool sched_in);