leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

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

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

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