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Date: Fri, 3 Jun 2016 03:49:28 -0700
From: tip-bot for Kan Liang <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: acme@...hat.com, torvalds@...ux-foundation.org,
ying.huang@...ux.intel.com, jolsa@...hat.com, hpa@...or.com,
kan.liang@...el.com, vincent.weaver@...ne.edu,
alexander.shishkin@...ux.intel.com, linux-kernel@...r.kernel.org,
peterz@...radead.org, tglx@...utronix.de, eranian@...gle.com,
mingo@...nel.org
Subject: [tip:perf/core] perf/core: Optimize side-band event delivery
Commit-ID: f2fb6bef92514432398a653df1c2f1041d79ac46
Gitweb: http://git.kernel.org/tip/f2fb6bef92514432398a653df1c2f1041d79ac46
Author: Kan Liang <kan.liang@...el.com>
AuthorDate: Wed, 23 Mar 2016 11:24:37 -0700
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 3 Jun 2016 09:40:15 +0200
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@...radead.org>
Reported-by: Huang, Ying <ying.huang@...ux.intel.com>
Signed-off-by: Kan Liang <kan.liang@...el.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Vince Weaver <vincent.weaver@...ne.edu>
Link: http://lkml.kernel.org/r/1458757477-3781-1-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
include/linux/perf_event.h | 6 ++++
kernel/events/core.c | 85 +++++++++++++++++++++++++++++++++++++++-------
2 files changed, 79 insertions(+), 12 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 0e43355..92e9ce7 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -517,6 +517,11 @@ struct swevent_hlist {
struct perf_cgroup;
struct ring_buffer;
+struct pmu_event_list {
+ raw_spinlock_t lock;
+ struct list_head list;
+};
+
/**
* struct perf_event - performance event kernel representation:
*/
@@ -675,6 +680,7 @@ struct perf_event {
int cgrp_defer_enabled;
#endif
+ struct list_head sb_list;
#endif /* CONFIG_PERF_EVENTS */
};
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 79363f2..6615c89 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));
}
}
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