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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2012-01-30 14:51:37 +0100
committerIngo Molnar <mingo@elte.hu>2012-02-22 12:06:55 +0100
commit8c79a045fd590a26e81e75f5d8d4ec5c7d23e565 (patch)
tree8123849709e37dc2394373ad40cf333b2f19ebb5 /kernel
parent719741d9986572d64b47c35c09f5e7bb8d389400 (diff)
downloadlinux-8c79a045fd590a26e81e75f5d8d4ec5c7d23e565.tar.bz2
sched/events: Revert trace_sched_stat_sleeptime()
Commit 1ac9bc69 ("sched/tracing: Add a new tracepoint for sleeptime") added a new sched:sched_stat_sleeptime tracepoint. It's broken: the first sample we get on a task might be bad because of a stale sleep_start value that wasn't reset at the last task switch because the tracepoint was not active. It also breaks the existing schedstat samples due to the side effects of: - se->statistics.sleep_start = 0; ... - se->statistics.block_start = 0; Nor do I see means to fix it without adding overhead to the scheduler fast path, which I'm not willing to for the sake of redundant instrumentation. Most importantly, sleep time information can already be constructed by tracing context switches and wakeups, and taking the timestamp difference between the schedule-out, the wakeup and the schedule-in. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrew Vagin <avagin@openvz.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/n/tip-pc4c9qhl8q6vg3bs4j6k0rbd@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c1
-rw-r--r--kernel/sched/fair.c2
2 files changed, 2 insertions, 1 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 5255c9d2e053..b342f57879e6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1932,7 +1932,6 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev)
local_irq_enable();
#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
finish_lock_switch(rq, prev);
- trace_sched_stat_sleeptime(current, rq->clock);
fire_sched_in_preempt_notifiers(current);
if (mm)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7c6414fc669d..aca16b843b7e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1003,6 +1003,7 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
if (unlikely(delta > se->statistics.sleep_max))
se->statistics.sleep_max = delta;
+ se->statistics.sleep_start = 0;
se->statistics.sum_sleep_runtime += delta;
if (tsk) {
@@ -1019,6 +1020,7 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
if (unlikely(delta > se->statistics.block_max))
se->statistics.block_max = delta;
+ se->statistics.block_start = 0;
se->statistics.sum_sleep_runtime += delta;
if (tsk) {