linux-kernel - [PATCH V3 4/5] perf/x86/intel: fix pmu read for large PEBS

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Message-Id: <1517243373-355481-5-git-send-email-kan.liang@linux.intel.com>
Date:   Mon, 29 Jan 2018 08:29:32 -0800
From:   kan.liang@...ux.intel.com
To:     peterz@...radead.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org
Cc:     acme@...nel.org, tglx@...utronix.de, jolsa@...hat.com,
        eranian@...gle.com, ak@...ux.intel.com,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH V3 4/5] perf/x86/intel: fix pmu read for large PEBS

From: Kan Liang <kan.liang@...ux.intel.com>

Large PEBS needs to be specially handled in event count read.

It is only available for intel_pmu.

Only need to specially handle the large PEBS. For the threshold is one,
even auto-reload is enabled, it doesn't need to be specially handled.
Because,
- auto-reload is only effect when event overflow. Once there is an
  overflow, the NMI handler will automatically drain_pebs().
- For other cases, x86_perf_event_update() is good enough.

Fixes: b8241d20699e ("perf/x86/intel: Implement batched PEBS interrupt
handling (large PEBS interrupt threshold)")
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 arch/x86/events/intel/core.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 731153a..1610a9d 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2060,6 +2060,14 @@ static void intel_pmu_del_event(struct perf_event *event)
 		intel_pmu_pebs_del(event);
 }
 
+static void intel_pmu_read_event(struct perf_event *event)
+{
+	if (intel_pmu_large_pebs_read(event))
+		return;
+
+	x86_perf_event_update(event);
+}
+
 static void intel_pmu_enable_fixed(struct hw_perf_event *hwc)
 {
 	int idx = hwc->idx - INTEL_PMC_IDX_FIXED;
@@ -3495,6 +3503,7 @@ static __initconst const struct x86_pmu intel_pmu = {
 	.disable		= intel_pmu_disable_event,
 	.add			= intel_pmu_add_event,
 	.del			= intel_pmu_del_event,
+	.read			= intel_pmu_read_event,
 	.hw_config		= intel_pmu_hw_config,
 	.schedule_events	= x86_schedule_events,
 	.eventsel		= MSR_ARCH_PERFMON_EVENTSEL0,
-- 
2.7.4