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Subject[PATCH 03/12] perf: add perf_event_task_migrate()
Date
Instead of calling perf_sw_event() directly from set_task_cpu(),
implement perf_event_task_migrate() which takes the same arguments as
trace_sched_migrate_task() and invokes perf_sw_event() is the task is
really migrating (cur_cpu != new_cpu). This will help unifying
notifiers in sched.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
---
include/linux/perf_event.h | 3 +++
kernel/perf_event.c | 11 +++++++++++
kernel/sched.c | 5 ++---
3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index c8e3754..a5eec48 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -754,6 +754,7 @@ extern int perf_max_events;

extern const struct pmu *hw_perf_event_init(struct perf_event *event);

+extern void perf_event_task_migrate(struct task_struct *task, int new_cpu);
extern void perf_event_task_sched_in(struct task_struct *task);
extern void perf_event_task_sched_out(struct task_struct *task, struct task_struct *next);
extern void perf_event_task_tick(struct task_struct *task);
@@ -949,6 +950,8 @@ extern void perf_event_enable(struct perf_event *event);
extern void perf_event_disable(struct perf_event *event);
#else
static inline void
+perf_event_task_migrate(struct task_struct *task, int new_cpu) { }
+static inline void
perf_event_task_sched_in(struct task_struct *task) { }
static inline void
perf_event_task_sched_out(struct task_struct *task,
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 3d1552d..a01ba31 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -1148,6 +1148,17 @@ static void perf_event_sync_stat(struct perf_event_context *ctx,
}

/*
+ * Called from scheduler set_task_cpu() to notify migration events.
+ * If the task is moving to a different cpu, generate a migration sw
+ * event.
+ */
+void perf_event_task_migrate(struct task_struct *task, int new_cpu)
+{
+ if (task_cpu(task) != new_cpu)
+ perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, 1, NULL, 0);
+}
+
+/*
* Called from scheduler to remove the events of the current task,
* with interrupts disabled.
*
diff --git a/kernel/sched.c b/kernel/sched.c
index c20fd31..2568911 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2084,11 +2084,10 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
#endif

trace_sched_migrate_task(p, new_cpu);
+ perf_event_task_migrate(p, new_cpu);

- if (task_cpu(p) != new_cpu) {
+ if (task_cpu(p) != new_cpu)
p->se.nr_migrations++;
- perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, 1, NULL, 0);
- }

__set_task_cpu(p, new_cpu);
}
--
1.6.4.2


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