diff options
| author | Frederic Weisbecker <fweisbec@gmail.com> | 2013-08-02 20:29:55 +0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-08-16 19:55:51 +0400 |
| commit | 948b26b6ddd08a57cb95ebb0dc96fde2edd5c383 (patch) | |
| tree | 7b358b7d8ab23ffadd170aba686768a74d7b8b01 | |
| parent | fc3b86d673e41ac66b4ba5b75a90c2fcafb90089 (diff) | |
| download | linux-948b26b6ddd08a57cb95ebb0dc96fde2edd5c383.tar.xz | |
perf: Account freq events globally
Freq events may not always be affine to a particular CPU. As such,
account_event_cpu() may crash if we account per cpu a freq event
that has event->cpu == -1.
To solve this, lets account freq events globally. In practice
this doesn't change much the picture because perf tools create
per-task perf events with one event per CPU by default. Profiling a
single CPU is usually a corner case so there is no much point in
optimizing things that way.
Reported-by: Jiri Olsa <jolsa@redhat.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Tested-by: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1375460996-16329-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | kernel/events/core.c | 19 |
1 files changed, 8 insertions, 11 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index e82e70025d42..2e675e830976 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -141,11 +141,11 @@ enum event_type_t { struct static_key_deferred perf_sched_events __read_mostly; static DEFINE_PER_CPU(atomic_t, perf_cgroup_events); static DEFINE_PER_CPU(atomic_t, perf_branch_stack_events); -static DEFINE_PER_CPU(atomic_t, perf_freq_events); static atomic_t nr_mmap_events __read_mostly; static atomic_t nr_comm_events __read_mostly; static atomic_t nr_task_events __read_mostly; +static atomic_t nr_freq_events __read_mostly; static LIST_HEAD(pmus); static DEFINE_MUTEX(pmus_lock); @@ -1871,9 +1871,6 @@ static int __perf_install_in_context(void *info) perf_pmu_enable(cpuctx->ctx.pmu); perf_ctx_unlock(cpuctx, task_ctx); - if (atomic_read(&__get_cpu_var(perf_freq_events))) - tick_nohz_full_kick(); - return 0; } @@ -2811,7 +2808,7 @@ done: #ifdef CONFIG_NO_HZ_FULL bool perf_event_can_stop_tick(void) { - if (atomic_read(&__get_cpu_var(perf_freq_events)) || + if (atomic_read(&nr_freq_events) || __this_cpu_read(perf_throttled_count)) return false; else @@ -3140,9 +3137,6 @@ static void unaccount_event_cpu(struct perf_event *event, int cpu) } if (is_cgroup_event(event)) atomic_dec(&per_cpu(perf_cgroup_events, cpu)); - - if (event->attr.freq) - atomic_dec(&per_cpu(perf_freq_events, cpu)); } static void unaccount_event(struct perf_event *event) @@ -3158,6 +3152,8 @@ static void unaccount_event(struct perf_event *event) atomic_dec(&nr_comm_events); if (event->attr.task) atomic_dec(&nr_task_events); + if (event->attr.freq) + atomic_dec(&nr_freq_events); if (is_cgroup_event(event)) static_key_slow_dec_deferred(&perf_sched_events); if (has_branch_stack(event)) @@ -6489,9 +6485,6 @@ static void account_event_cpu(struct perf_event *event, int cpu) } if (is_cgroup_event(event)) atomic_inc(&per_cpu(perf_cgroup_events, cpu)); - - if (event->attr.freq) - atomic_inc(&per_cpu(perf_freq_events, cpu)); } static void account_event(struct perf_event *event) @@ -6507,6 +6500,10 @@ static void account_event(struct perf_event *event) atomic_inc(&nr_comm_events); if (event->attr.task) atomic_inc(&nr_task_events); + if (event->attr.freq) { + if (atomic_inc_return(&nr_freq_events) == 1) + tick_nohz_full_kick_all(); + } if (has_branch_stack(event)) static_key_slow_inc(&perf_sched_events.key); if (is_cgroup_event(event)) |