[PATCH 07/12] sched: coalesce event notifiers

Tejun Heo
2010-05-04T12:39:19Z

sched currently hosts three different event notification mechanisms -
tracepoints, perf_event functions and sched_notifiers. The previous
patches modified and moved them around so that they are colocated
where applicable and share most of the arguments. This patch
introduces and uses SCHED_EVENT() and SCHED_EVENT_RQ() to coalesce
calls to different mechanisms.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
---
kernel/sched.c | 51 ++++++++++++++++++++++++++++++++++++++++-----------
1 files changed, 40 insertions(+), 11 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 0b753f0..1acec30 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1439,6 +1439,39 @@ static inline void fire_sched_notifiers_in(struct task_struct *p)
fire_sched_notifiers(in, p);
}

+/*
+ * Sched is watched by three different mechanisms - tracepoint,
+ * perf_event and sched_notifiers. SCHED_EVENT*() can be used to
+ * define all or any part of them at once so that code clutter is kept
+ * to minimum and optimizations can be applied according to different
+ * config options.
+ *
+ * In SCHED_EVENT(), the first three arguments specify the name of
+ * tracepoint, perf_event and sched_notifier. NONE can be used to
+ * omit any subset of the three. The last argument is event arguments
+ * wrapped inside SE_ARGS() macro.
+ *
+ * SCHED_EVENT_RQ() is identical except that @rq argument will be
+ * added to tracepoint and perf calls.
+ */
+#define trace_sched_NONE(args...) do { } while (0)
+#define perf_event_task_NONE(args...) do { } while (0)
+#define fire_sched_notifiers_NONE(args...) do { } while (0)
+
+#define SE_ARGS(args...) args
+
+#define SCHED_EVENT(TP, PERF, SN, args) do { \
+ trace_sched_##TP(args); \
+ perf_event_task_##PERF(args); \
+ fire_sched_notifiers_##SN(args); \
+} while (0)
+
+#define SCHED_EVENT_RQ(TP, PERF, SN, rq, args) do { \
+ trace_sched_##TP(rq, args); \
+ perf_event_task_##PERF(rq, args); \
+ fire_sched_notifiers_##SN(args); \
+} while (0)
+
static inline void inc_cpu_load(struct rq *rq, unsigned long load)
{
update_load_add(&rq->load, load);
@@ -2083,8 +2116,7 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
!(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE));
#endif

- trace_sched_migrate_task(p, new_cpu);
- perf_event_task_migrate(p, new_cpu);
+ SCHED_EVENT(migrate_task, migrate, NONE, SE_ARGS(p, new_cpu));

if (task_cpu(p) != new_cpu)
p->se.nr_migrations++;
@@ -2223,7 +2255,7 @@ unsigned long wait_task_inactive(struct task_struct *p, long match_state)
* just go back and repeat.
*/
rq = task_rq_lock(p, &flags);
- trace_sched_wait_task(rq, p);
+ SCHED_EVENT_RQ(wait_task, NONE, NONE, rq, SE_ARGS(p));
running = task_running(rq, p);
on_rq = p->se.on_rq;
ncsw = 0;
@@ -2515,7 +2547,7 @@ out_activate:
}

out_running:
- trace_sched_wakeup(rq, p, success);
+ SCHED_EVENT_RQ(wakeup, NONE, NONE, rq, SE_ARGS(p, success));
check_preempt_curr(rq, p, wake_flags);

p->state = TASK_RUNNING;
@@ -2726,7 +2758,7 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
p->state = TASK_RUNNING;
update_rq_clock(rq);
activate_task(rq, p, 0);
- trace_sched_wakeup_new(rq, p, 1);
+ SCHED_EVENT_RQ(wakeup_new, NONE, NONE, rq, SE_ARGS(p, 1));
check_preempt_curr(rq, p, WF_FORK);
#ifdef CONFIG_SMP
if (p->sched_class->task_woken)
@@ -2795,8 +2827,7 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev)
finish_arch_switch(prev);
finish_lock_switch(rq, prev);

- perf_event_task_sched_in(current);
- fire_sched_notifiers_in(current);
+ SCHED_EVENT(NONE, sched_in, in, SE_ARGS(current));
if (mm)
mmdrop(mm);
if (unlikely(prev_state == TASK_DEAD)) {
@@ -3498,7 +3529,7 @@ void scheduler_tick(void)
curr->sched_class->task_tick(rq, curr, 0);
raw_spin_unlock(&rq->lock);

- perf_event_task_tick(curr);
+ SCHED_EVENT(NONE, tick, NONE, SE_ARGS(curr));

#ifdef CONFIG_SMP
rq->idle_at_tick = idle_cpu(cpu);
@@ -3712,9 +3743,7 @@ need_resched_nonpreemptible:

if (likely(prev != next)) {
sched_info_switch(prev, next);
- trace_sched_switch(rq, prev, next);
- perf_event_task_sched_out(rq, prev, next);
- fire_sched_notifiers_out(prev, next);
+ SCHED_EVENT_RQ(switch, sched_out, out, rq, SE_ARGS(prev, next));

rq->nr_switches++;
rq->curr = next;
--
1.6.4.2