Commit-ID: 948b26b6ddd08a57cb95ebb0dc96fde2edd5c383
Gitweb: http://git.kernel.org/tip/948b26b6ddd08a57cb95ebb0dc96fde2edd5c383
Author: Frederic Weisbecker <fweisbec@xxxxxxxxx>
AuthorDate: Fri, 2 Aug 2013 18:29:55 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 16 Aug 2013 17:55:51 +0200
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@xxxxxxxxxx>
Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Tested-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1375460996-16329-3-git-send-email-fweisbec@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/events/core.c | 19 ++++++++-----------
1 file changed, 8 insertions(+), 11 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index e82e700..2e675e8 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))
--
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