perf/core: Optimize ctx_sched_out()

When an event group contains more events than can be scheduled on the
hardware, iterating the full event group for ctx_sched_out is a waste
of time.

Keep track of the events that got programmed on the hardware, such
that we can iterate this smaller list in order to schedule them out.

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: Peter Zijlstra <peterz@infradead.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>

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 84044ec21b316d257d46fdf5cc783cbfb94db2b8..2bb200e1bbea16476bb4a2c5ea7c2a6bce692d26 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -553,6 +553,7 @@ struct perf_event {
         * either sufficies for read.
         */
        struct list_head                sibling_list;
+       struct list_head                active_list;
        /*
         * Node on the pinned or flexible tree located at the event context;
         */
@@ -718,6 +719,10 @@ struct perf_event_context {
        struct perf_event_groups        pinned_groups;
        struct perf_event_groups        flexible_groups;
        struct list_head                event_list;
+
+       struct list_head                pinned_active;
+       struct list_head                flexible_active;
+
        int                             nr_events;
        int                             nr_active;
        int                             is_active;

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9a07bbe664510d1a8428b42621a281538feaf4ac..4d601c06074f559dd726acd740560deb5a22a7dd 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1647,14 +1647,6 @@ perf_event_groups_rotate(struct perf_event_groups *groups, int cpu)
                                typeof(*event), node); event;   \
                event = rb_entry_safe(rb_next(&event->node),    \
                                typeof(*event), node))
-/*
- * Iterate event groups with cpu == key.
- */
-#define perf_event_groups_for_each_cpu(event, key, groups, node) \
-       for (event = perf_event_groups_first(groups, key);       \
-               event && event->cpu == key;                      \
-               event = rb_entry_safe(rb_next(&event->node),     \
-                               typeof(*event), node))
 
 /*
  * Add a event from the lists for its context.
@@ -1889,8 +1881,9 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx)
 static void perf_group_detach(struct perf_event *event)
 {
        struct perf_event *sibling, *tmp;
+       struct perf_event_context *ctx = event->ctx;
 
-       lockdep_assert_held(&event->ctx->lock);
+       lockdep_assert_held(&ctx->lock);
 
        /*
         * We can have double detach due to exit/hot-unplug + close.
@@ -1924,6 +1917,13 @@ static void perf_group_detach(struct perf_event *event)
                if (!RB_EMPTY_NODE(&event->group_node)) {
                        list_del_init(&sibling->sibling_list);
                        add_event_to_groups(sibling, event->ctx);
+
+                       if (sibling->state == PERF_EVENT_STATE_ACTIVE) {
+                               struct list_head *list = sibling->attr.pinned ?
+                                       &ctx->pinned_active : &ctx->flexible_active;
+
+                               list_add_tail(&sibling->active_list, list);
+                       }
                }
 
                WARN_ON_ONCE(sibling->ctx != event->ctx);
@@ -1988,6 +1988,13 @@ event_sched_out(struct perf_event *event,
        if (event->state != PERF_EVENT_STATE_ACTIVE)
                return;
 
+       /*
+        * Asymmetry; we only schedule events _IN_ through ctx_sched_in(), but
+        * we can schedule events _OUT_ individually through things like
+        * __perf_remove_from_context().
+        */
+       list_del_init(&event->active_list);
+
        perf_pmu_disable(event->pmu);
 
        event->pmu->del(event, 0);
@@ -2835,9 +2842,8 @@ static void ctx_sched_out(struct perf_event_context *ctx,
                          struct perf_cpu_context *cpuctx,
                          enum event_type_t event_type)
 {
-       int sw = -1, cpu = smp_processor_id();
+       struct perf_event *event, *tmp;
        int is_active = ctx->is_active;
-       struct perf_event *event;
 
        lockdep_assert_held(&ctx->lock);
 
@@ -2884,20 +2890,12 @@ static void ctx_sched_out(struct perf_event_context *ctx,
 
        perf_pmu_disable(ctx->pmu);
        if (is_active & EVENT_PINNED) {
-               perf_event_groups_for_each_cpu(event, cpu,
-                               &ctx->pinned_groups, group_node)
-                       group_sched_out(event, cpuctx, ctx);
-               perf_event_groups_for_each_cpu(event, sw,
-                               &ctx->pinned_groups, group_node)
+               list_for_each_entry_safe(event, tmp, &ctx->pinned_active, active_list)
                        group_sched_out(event, cpuctx, ctx);
        }
 
        if (is_active & EVENT_FLEXIBLE) {
-               perf_event_groups_for_each_cpu(event, cpu,
-                               &ctx->flexible_groups, group_node)
-                       group_sched_out(event, cpuctx, ctx);
-               perf_event_groups_for_each_cpu(event, sw,
-                               &ctx->flexible_groups, group_node)
+               list_for_each_entry_safe(event, tmp, &ctx->flexible_active, active_list)
                        group_sched_out(event, cpuctx, ctx);
        }
        perf_pmu_enable(ctx->pmu);
@@ -3231,8 +3229,10 @@ static int pinned_sched_in(struct perf_event *event, void *data)
        if (!event_filter_match(event))
                return 0;
 
-       if (group_can_go_on(event, sid->cpuctx, sid->can_add_hw))
-               group_sched_in(event, sid->cpuctx, sid->ctx);
+       if (group_can_go_on(event, sid->cpuctx, sid->can_add_hw)) {
+               if (!group_sched_in(event, sid->cpuctx, sid->ctx))
+                       list_add_tail(&event->active_list, &sid->ctx->pinned_active);
+       }
 
        /*
         * If this pinned group hasn't been scheduled,
@@ -3255,7 +3255,9 @@ static int flexible_sched_in(struct perf_event *event, void *data)
                return 0;
 
        if (group_can_go_on(event, sid->cpuctx, sid->can_add_hw)) {
-               if (group_sched_in(event, sid->cpuctx, sid->ctx))
+               if (!group_sched_in(event, sid->cpuctx, sid->ctx))
+                       list_add_tail(&event->active_list, &sid->ctx->flexible_active);
+               else
                        sid->can_add_hw = 0;
        }
 
@@ -3973,6 +3975,8 @@ static void __perf_event_init_context(struct perf_event_context *ctx)
        perf_event_groups_init(&ctx->pinned_groups);
        perf_event_groups_init(&ctx->flexible_groups);
        INIT_LIST_HEAD(&ctx->event_list);
+       INIT_LIST_HEAD(&ctx->pinned_active);
+       INIT_LIST_HEAD(&ctx->flexible_active);
        atomic_set(&ctx->refcount, 1);
 }
 
@@ -9815,6 +9819,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 
        INIT_LIST_HEAD(&event->event_entry);
        INIT_LIST_HEAD(&event->sibling_list);
+       INIT_LIST_HEAD(&event->active_list);
        init_event_group(event);
        INIT_LIST_HEAD(&event->rb_entry);
        INIT_LIST_HEAD(&event->active_entry);