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authorAlexander Shishkin <alexander.shishkin@linux.intel.com>2017-01-19 17:43:29 +0100
committerIngo Molnar <mingo@kernel.org>2017-01-30 12:01:14 +0100
commitfe45bafbd0e1b5e828aa9d44d07e569df85869a2 (patch)
tree3edb6f4db8cf67e2c38e03301952c2c5e10d7d42
parentperf/core: Remove perf_cpu_context::unique_pmu (diff)
downloadlinux-fe45bafbd0e1b5e828aa9d44d07e569df85869a2.tar.xz
linux-fe45bafbd0e1b5e828aa9d44d07e569df85869a2.zip
perf/core: Don't re-schedule CPU flexible events needlessly
In the sched-in path, we first remove a CPU's flexible events in order to give priority to the task's pinned events. However, this step can be safely skipped if the task doesn't have its own pinned events. This patch implements this skipping. Reported-by: Adrian Hunter <adrian.hunter@intel.com> Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: vince@deater.net Link: http://lkml.kernel.org/r/20170119164330.22887-2-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--kernel/events/core.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index d92c7ad7715d..8c0b7334230b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3122,8 +3122,12 @@ static void perf_event_context_sched_in(struct perf_event_context *ctx,
* We want to keep the following priority order:
* cpu pinned (that don't need to move), task pinned,
* cpu flexible, task flexible.
+ *
+ * However, if task's ctx is not carrying any pinned
+ * events, no need to flip the cpuctx's events around.
*/
- cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
+ if (!list_empty(&ctx->pinned_groups))
+ cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
perf_event_sched_in(cpuctx, ctx, task);
perf_pmu_enable(ctx->pmu);
perf_ctx_unlock(cpuctx, ctx);