From: kan.liang@linux.intel.com
To: peterz@infradead.org, mingo@redhat.com, linux-kernel@vger.kernel.org
Cc: acme@kernel.org, tglx@linutronix.de, jolsa@redhat.com,
eranian@google.com, ak@linux.intel.com,
Kan Liang <kan.liang@linux.intel.com>
Subject: [PATCH V3 3/5] perf/x86/intel/ds: introduce read function for large pebs
Date: Mon, 29 Jan 2018 08:29:31 -0800 [thread overview]
Message-ID: <1517243373-355481-4-git-send-email-kan.liang@linux.intel.com> (raw)
In-Reply-To: <1517243373-355481-1-git-send-email-kan.liang@linux.intel.com>
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
next prev parent reply other threads:[~2018-01-29 16:31 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-29 16:29 [PATCH V3 0/5] bugs fix for large PEBS mmap read and rdpmc read kan.liang
2018-01-29 16:29 ` [PATCH V3 1/5] perf/x86/intel: fix event update for auto-reload kan.liang
2018-02-06 15:06 ` Peter Zijlstra
2018-02-06 17:58 ` Liang, Kan
2018-02-09 14:09 ` Peter Zijlstra
2018-02-09 15:49 ` Liang, Kan
2018-02-10 14:09 ` Peter Zijlstra
2018-01-29 16:29 ` [PATCH V3 2/5] perf/x86: introduce read function for x86_pmu kan.liang
2018-01-29 16:29 ` kan.liang [this message]
2018-01-29 16:29 ` [PATCH V3 4/5] perf/x86/intel: fix pmu read for large PEBS kan.liang
2018-01-29 16:29 ` [PATCH V3 5/5] perf/x86: fix: disable userspace RDPMC usage " kan.liang
2018-01-30 9:16 ` [PATCH V3 0/5] bugs fix for large PEBS mmap read and rdpmc read Stephane Eranian
2018-01-30 13:39 ` Jiri Olsa
2018-01-30 14:59 ` Liang, Kan
2018-01-30 15:04 ` Jiri Olsa
2018-01-30 15:25 ` Liang, Kan
2018-01-30 16:36 ` Stephane Eranian
2018-01-30 16:48 ` Liang, Kan
2018-01-30 18:52 ` Jiri Olsa
2018-01-30 19:56 ` Stephane Eranian
2018-01-31 3:59 ` Andi Kleen
2018-01-31 9:15 ` Jiri Olsa
2018-01-31 13:15 ` Jiri Olsa
2018-01-31 15:15 ` Liang, Kan
2018-01-31 15:41 ` Jiri Olsa
2018-01-30 14:41 ` Liang, Kan
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