diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-11-27 14:12:25 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-09-20 13:17:58 -0700 |
| commit | 55eedcb291d0c7dd1a56090f72c80360fbb40d2f (patch) | |
| tree | a19c0376eb685eb544093390daf97a5bacd4223a /kernel | |
| parent | 9c6abb9b9806aa822c1e3ad924434c42ce0206ef (diff) | |
sched: Remove rq->clock coupling from set_task_cpu()
commit 5afcdab706d6002cb02b567ba46e650215e694e8 upstream
set_task_cpu() should be rq invariant and only touch task state, it
currently fails to do so, which opens up a few races, since not all
callers hold both rq->locks.
Remove the relyance on rq->clock, as any site calling set_task_cpu()
should also do a remote clock update, which should ensure the observed
time between these two cpus is monotonic, as per
kernel/sched_clock.c:sched_clock_remote().
Therefore we can simply remove the clock_offset bits and be happy.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched.c | 13 |
1 files changed, 1 insertions, 12 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 103d120308e..e3d92940c66 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2069,23 +2069,12 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd) void set_task_cpu(struct task_struct *p, unsigned int new_cpu) { int old_cpu = task_cpu(p); - struct rq *old_rq = cpu_rq(old_cpu), *new_rq = cpu_rq(new_cpu); + struct rq *old_rq = cpu_rq(old_cpu); struct cfs_rq *old_cfsrq = task_cfs_rq(p), *new_cfsrq = cpu_cfs_rq(old_cfsrq, new_cpu); - u64 clock_offset; - - clock_offset = old_rq->clock - new_rq->clock; trace_sched_migrate_task(p, new_cpu); -#ifdef CONFIG_SCHEDSTATS - if (p->se.wait_start) - p->se.wait_start -= clock_offset; - if (p->se.sleep_start) - p->se.sleep_start -= clock_offset; - if (p->se.block_start) - p->se.block_start -= clock_offset; -#endif if (old_cpu != new_cpu) { p->se.nr_migrations++; #ifdef CONFIG_SCHEDSTATS |