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authorPeter Zijlstra <peterz@infradead.org>2017-11-13 14:28:44 +0100
committerIngo Molnar <mingo@kernel.org>2018-03-12 15:28:50 +0100
commit8703a7cfe148f73062c568e9a8549ce692104864 (patch)
tree074000272c91b34f204800673289d999777d4861 /kernel/events
parent6e6804d2fa0eff6520f3a2b48ff52bcb9dc25a9d (diff)
perf/core: Fix tree based event rotation
Similar to how first programming cpu=-1 and then cpu=# is wrong, so is rotating both. It was especially wrong when we were still programming the PMU in this same order, because in that scenario we might never actually end up running cpu=# events at all. Cure this by using the active_list to pick the rotation event; since at programming we already select the left-most event. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Alexey Budankov <alexey.budankov@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: David Carrillo-Cisneros <davidcc@google.com> Cc: Dmitri Prokhorov <Dmitry.Prohorov@intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Kan Liang <kan.liang@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Valery Cherepennikov <valery.cherepennikov@intel.com> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/core.c44
1 files changed, 18 insertions, 26 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index fc5dd072c194..460e485220e8 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1624,22 +1624,6 @@ perf_event_groups_next(struct perf_event *event)
}
/*
- * Rotate the @cpu subtree.
- *
- * Re-insert the leftmost event at the tail of the subtree.
- */
-static void
-perf_event_groups_rotate(struct perf_event_groups *groups, int cpu)
-{
- struct perf_event *event = perf_event_groups_first(groups, cpu);
-
- if (event) {
- perf_event_groups_delete(groups, event);
- perf_event_groups_insert(groups, event);
- }
-}
-
-/*
* Iterate through the whole groups tree.
*/
#define perf_event_groups_for_each(event, groups) \
@@ -3601,24 +3585,24 @@ static void perf_adjust_freq_unthr_context(struct perf_event_context *ctx,
}
/*
- * Round-robin a context's events:
+ * Move @event to the tail of the @ctx's elegible events.
*/
-static void rotate_ctx(struct perf_event_context *ctx)
+static void rotate_ctx(struct perf_event_context *ctx, struct perf_event *event)
{
/*
* Rotate the first entry last of non-pinned groups. Rotation might be
* disabled by the inheritance code.
*/
- if (!ctx->rotate_disable) {
- int sw = -1, cpu = smp_processor_id();
+ if (ctx->rotate_disable)
+ return;
- perf_event_groups_rotate(&ctx->flexible_groups, sw);
- perf_event_groups_rotate(&ctx->flexible_groups, cpu);
- }
+ perf_event_groups_delete(&ctx->flexible_groups, event);
+ perf_event_groups_insert(&ctx->flexible_groups, event);
}
static int perf_rotate_context(struct perf_cpu_context *cpuctx)
{
+ struct perf_event *ctx_event = NULL, *cpuctx_event = NULL;
struct perf_event_context *ctx = NULL;
int rotate = 0;
@@ -3639,13 +3623,21 @@ static int perf_rotate_context(struct perf_cpu_context *cpuctx)
perf_ctx_lock(cpuctx, cpuctx->task_ctx);
perf_pmu_disable(cpuctx->ctx.pmu);
+ cpuctx_event = list_first_entry_or_null(&cpuctx->ctx.flexible_active,
+ struct perf_event, active_list);
+ if (ctx) {
+ ctx_event = list_first_entry_or_null(&ctx->flexible_active,
+ struct perf_event, active_list);
+ }
+
cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
if (ctx)
ctx_sched_out(ctx, cpuctx, EVENT_FLEXIBLE);
- rotate_ctx(&cpuctx->ctx);
- if (ctx)
- rotate_ctx(ctx);
+ if (cpuctx_event)
+ rotate_ctx(&cpuctx->ctx, cpuctx_event);
+ if (ctx_event)
+ rotate_ctx(ctx, ctx_event);
perf_event_sched_in(cpuctx, ctx, current);