From: Alexey Budankov <alexey.budankov@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Andi Kleen <ak@linux.intel.com>,
Kan Liang <kan.liang@linux.intel.com>,
Stephane Eranian <eranian@google.com>,
Ian Rogers <irogers@google.com>, Song Liu <songliubraving@fb.com>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: [PATCH v3 4/4] perf/core,x86: synchronize PMU task contexts on optimized context switches
Date: Wed, 16 Oct 2019 17:28:17 +0300 [thread overview]
Message-ID: <729e8b40-0d96-9df7-fc86-b7309df94bc9@linux.intel.com> (raw)
In-Reply-To: <792a98c7-ed89-6c35-f1d7-98ddc9c1a117@linux.intel.com>
Install Intel specific PMU task context synchronization adapter and
extend optimized context switch path with PMU specific task context
synchronization to fix LBR callstack virtualization on context switches.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
arch/x86/events/intel/core.c | 7 +++++++
kernel/events/core.c | 9 +++++++++
2 files changed, 16 insertions(+)
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 43c966d1208e..7cfa658cce4b 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3819,6 +3819,12 @@ static void intel_pmu_sched_task(struct perf_event_context *ctx,
intel_pmu_lbr_sched_task(ctx, sched_in);
}
+static void intel_pmu_sync_task_ctx(struct x86_perf_task_context *one,
+ struct x86_perf_task_context *another)
+{
+ intel_pmu_lbr_sync_task_ctx(one, another);
+}
+
static int intel_pmu_check_period(struct perf_event *event, u64 value)
{
return intel_pmu_has_bts_period(event, value) ? -EINVAL : 0;
@@ -3954,6 +3960,7 @@ static __initconst const struct x86_pmu intel_pmu = {
.guest_get_msrs = intel_guest_get_msrs,
.sched_task = intel_pmu_sched_task,
+ .sync_task_ctx = intel_pmu_sync_task_ctx,
.check_period = intel_pmu_check_period,
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 2aad959e6def..3c7edd8454ef 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3204,11 +3204,20 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn,
raw_spin_lock(&ctx->lock);
raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);
if (context_equiv(ctx, next_ctx)) {
+ struct pmu *pmu = ctx->pmu;
+
WRITE_ONCE(ctx->task, next);
WRITE_ONCE(next_ctx->task, task);
swap(ctx->task_ctx_data, next_ctx->task_ctx_data);
+ /*
+ * PMU specific parts of task perf context may require
+ * additional synchronization, at least for proper Intel
+ * LBR callstack data profiling;
+ */
+ pmu->sync_task_ctx(ctx->task_ctx_data,
+ next_ctx->task_ctx_data);
/*
* RCU_INIT_POINTER here is safe because we've not
* modified the ctx and the above modification of
--
2.20.1
next prev parent reply other threads:[~2019-10-16 14:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-16 14:20 [PATCH v3 0/4]: perf/core: fix restoring of Intel LBR call stack on a context switch Alexey Budankov
2019-10-16 14:25 ` [PATCH v3 1/4] perf/core,x86: introduce sync_task_ctx() method at struct pmu Alexey Budankov
2019-10-16 14:26 ` [PATCH v3 2/4] perf/x86: install platform specific sync_task_ctx adapter Alexey Budankov
2019-10-16 14:27 ` [PATCH v3 3/4] perf/x86/intel: implement LBR callstacks context synchronization Alexey Budankov
2019-10-16 14:28 ` Alexey Budankov [this message]
2019-10-18 9:17 [PATCH v3 0/4]: perf/core: fix restoring of Intel LBR call stack on a context switch Alexey Budankov
2019-10-18 9:45 ` [PATCH v3 4/4] perf/core,x86: synchronize PMU task contexts on optimized context switches Alexey Budankov
2019-10-21 7:59 ` Ingo Molnar
2019-10-21 10:00 ` Alexey Budankov
2019-10-21 10:37 ` Peter Zijlstra
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