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authorKan Liang <kan.liang@intel.com>2016-03-23 11:24:37 -0700
committerIngo Molnar <mingo@kernel.org>2016-06-03 09:40:15 +0200
commitf2fb6bef92514432398a653df1c2f1041d79ac46 (patch)
tree4d576da877bc1ff5ee08f81d53339b91ea04ced8 /kernel/events/core.c
parent42c4fb774782eead571f7379edf16b1138e7cebb (diff)
perf/core: Optimize side-band event delivery
The perf_event_aux() function iterates all PMUs and all events in their respective per-CPU contexts to find the events to deliver side-band records to. For example, the brk test case in lkp triggers many mmap() operations, which, if we're also running perf, results in many perf_event_aux() invocations. If we enable uncore PMU support (even when uncore events are not used), dozens of uncore PMUs will be iterated, which can significantly decrease brk_test's throughput. For example, the brk throughput: without uncore PMUs: 2647573 ops_per_sec with uncore PMUs: 1768444 ops_per_sec ... a 33% reduction. To get at the per-CPU events that need side-band records, this patch puts these events on a per-CPU list, this avoids iterating the PMUs and any events that do not need side-band records. Per task events are unchanged to avoid extra overhead on the context switch paths. Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reported-by: Huang, Ying <ying.huang@linux.intel.com> Signed-off-by: Kan Liang <kan.liang@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@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> Link: http://lkml.kernel.org/r/1458757477-3781-1-git-send-email-kan.liang@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events/core.c')
-rw-r--r--kernel/events/core.c85
1 files changed, 73 insertions, 12 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 79363f298445..6615c8922ee3 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -335,6 +335,7 @@ static atomic_t perf_sched_count;
static DEFINE_PER_CPU(atomic_t, perf_cgroup_events);
static DEFINE_PER_CPU(int, perf_sched_cb_usages);
+static DEFINE_PER_CPU(struct pmu_event_list, pmu_sb_events);
static atomic_t nr_mmap_events __read_mostly;
static atomic_t nr_comm_events __read_mostly;
@@ -3665,6 +3666,26 @@ static void free_event_rcu(struct rcu_head *head)
static void ring_buffer_attach(struct perf_event *event,
struct ring_buffer *rb);
+static void detach_sb_event(struct perf_event *event)
+{
+ struct pmu_event_list *pel = per_cpu_ptr(&pmu_sb_events, event->cpu);
+
+ raw_spin_lock(&pel->lock);
+ list_del_rcu(&event->sb_list);
+ raw_spin_unlock(&pel->lock);
+}
+
+static void unaccount_pmu_sb_event(struct perf_event *event)
+{
+ if (event->parent)
+ return;
+
+ if (event->attach_state & PERF_ATTACH_TASK)
+ return;
+
+ detach_sb_event(event);
+}
+
static void unaccount_event_cpu(struct perf_event *event, int cpu)
{
if (event->parent)
@@ -3728,6 +3749,8 @@ static void unaccount_event(struct perf_event *event)
}
unaccount_event_cpu(event, event->cpu);
+
+ unaccount_pmu_sb_event(event);
}
static void perf_sched_delayed(struct work_struct *work)
@@ -5888,13 +5911,25 @@ perf_event_aux_task_ctx(perf_event_aux_output_cb output, void *data,
rcu_read_unlock();
}
+static void perf_event_sb_iterate(perf_event_aux_output_cb output, void *data)
+{
+ struct pmu_event_list *pel = this_cpu_ptr(&pmu_sb_events);
+ struct perf_event *event;
+
+ list_for_each_entry_rcu(event, &pel->list, sb_list) {
+ if (event->state < PERF_EVENT_STATE_INACTIVE)
+ continue;
+ if (!event_filter_match(event))
+ continue;
+ output(event, data);
+ }
+}
+
static void
perf_event_aux(perf_event_aux_output_cb output, void *data,
struct perf_event_context *task_ctx)
{
- struct perf_cpu_context *cpuctx;
struct perf_event_context *ctx;
- struct pmu *pmu;
int ctxn;
/*
@@ -5909,20 +5944,15 @@ perf_event_aux(perf_event_aux_output_cb output, void *data,
}
rcu_read_lock();
- list_for_each_entry_rcu(pmu, &pmus, entry) {
- cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
- if (cpuctx->unique_pmu != pmu)
- goto next;
- perf_event_aux_ctx(&cpuctx->ctx, output, data, false);
- ctxn = pmu->task_ctx_nr;
- if (ctxn < 0)
- goto next;
+ preempt_disable();
+ perf_event_sb_iterate(output, data);
+
+ for_each_task_context_nr(ctxn) {
ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
if (ctx)
perf_event_aux_ctx(ctx, output, data, false);
-next:
- put_cpu_ptr(pmu->pmu_cpu_context);
}
+ preempt_enable();
rcu_read_unlock();
}
@@ -8615,6 +8645,32 @@ unlock:
return pmu;
}
+static void attach_sb_event(struct perf_event *event)
+{
+ struct pmu_event_list *pel = per_cpu_ptr(&pmu_sb_events, event->cpu);
+
+ raw_spin_lock(&pel->lock);
+ list_add_rcu(&event->sb_list, &pel->list);
+ raw_spin_unlock(&pel->lock);
+}
+
+static void account_pmu_sb_event(struct perf_event *event)
+{
+ struct perf_event_attr *attr = &event->attr;
+
+ if (event->parent)
+ return;
+
+ if (event->attach_state & PERF_ATTACH_TASK)
+ return;
+
+ if (attr->mmap || attr->mmap_data || attr->mmap2 ||
+ attr->comm || attr->comm_exec ||
+ attr->task ||
+ attr->context_switch)
+ attach_sb_event(event);
+}
+
static void account_event_cpu(struct perf_event *event, int cpu)
{
if (event->parent)
@@ -8695,6 +8751,8 @@ static void account_event(struct perf_event *event)
enabled:
account_event_cpu(event, event->cpu);
+
+ account_pmu_sb_event(event);
}
/*
@@ -10203,6 +10261,9 @@ static void __init perf_event_init_all_cpus(void)
swhash = &per_cpu(swevent_htable, cpu);
mutex_init(&swhash->hlist_mutex);
INIT_LIST_HEAD(&per_cpu(active_ctx_list, cpu));
+
+ INIT_LIST_HEAD(&per_cpu(pmu_sb_events.list, cpu));
+ raw_spin_lock_init(&per_cpu(pmu_sb_events.lock, cpu));
}
}