diff options
author | Kan Liang <kan.liang@intel.com> | 2016-03-23 11:24:37 -0700 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2016-06-03 09:40:15 +0200 |
commit | f2fb6bef92514432398a653df1c2f1041d79ac46 (patch) | |
tree | 4d576da877bc1ff5ee08f81d53339b91ea04ced8 /kernel | |
parent | 42c4fb774782eead571f7379edf16b1138e7cebb (diff) | |
download | op-kernel-dev-f2fb6bef92514432398a653df1c2f1041d79ac46.zip op-kernel-dev-f2fb6bef92514432398a653df1c2f1041d79ac46.tar.gz |
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')
-rw-r--r-- | kernel/events/core.c | 85 |
1 files changed, 73 insertions, 12 deletions
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)); } } |