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perf/core: Fix tree based event rotation

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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>
This commit is contained in:
Peter Zijlstra 2017-11-13 14:28:44 +01:00 committed by Ingo Molnar
parent 6e6804d2fa
commit 8703a7cfe1
1 changed files with 18 additions and 26 deletions
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44
kernel/events/core.c
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@ -1623,22 +1623,6 @@ perf_event_groups_next(struct perf_event *event)
return NULL;
}
/*
* 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.
*/
@ -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);