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perf/x86: Synchronize PMU task contexts on optimized context switches

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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>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: https://lkml.kernel.org/r/9c6445a9-bdba-ef03-3859-f1f91198f27a@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Alexey Budankov 2019-10-23 10:13:56 +03:00 committed by Ingo Molnar
parent 421ca868ea
commit c2b98a8661
2 changed files with 19 additions and 1 deletions
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7
arch/x86/events/intel/core.c
View file

@ -3820,6 +3820,12 @@ static void intel_pmu_sched_task(struct perf_event_context *ctx,
intel_pmu_lbr_sched_task(ctx, sched_in);
}
static void intel_pmu_swap_task_ctx(struct perf_event_context *prev,
struct perf_event_context *next)
{
intel_pmu_lbr_swap_task_ctx(prev, next);
}
static int intel_pmu_check_period(struct perf_event *event, u64 value)
{
return intel_pmu_has_bts_period(event, value) ? -EINVAL : 0;
@ -3955,6 +3961,7 @@ static __initconst const struct x86_pmu intel_pmu = {
.guest_get_msrs = intel_guest_get_msrs,
.sched_task = intel_pmu_sched_task,
.swap_task_ctx = intel_pmu_swap_task_ctx,
.check_period = intel_pmu_check_period,

13
kernel/events/core.c
View file

@ -3204,10 +3204,21 @@ 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 can require
* additional synchronization. As an example of such
* synchronization see implementation details of Intel
* LBR call stack data profiling;
*/
if (pmu->swap_task_ctx)
pmu->swap_task_ctx(ctx, next_ctx);
else
swap(ctx->task_ctx_data, next_ctx->task_ctx_data);
/*
* RCU_INIT_POINTER here is safe because we've not