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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-11-27 14:12:25 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-12-09 10:03:03 +0100 |
| commit | 5afcdab706d6002cb02b567ba46e650215e694e8 (patch) | |
| tree | 015c3fb61dc8a4217bc83927efd7882e7d494d2b /kernel/sched.c | |
| parent | 970b13bacba14a8cef6f642861947df1d175b0b3 (diff) | |
| download | linux-5afcdab706d6002cb02b567ba46e650215e694e8.tar.gz linux-5afcdab706d6002cb02b567ba46e650215e694e8.tar.bz2 linux-5afcdab706d6002cb02b567ba46e650215e694e8.zip | |
sched: Remove rq->clock coupling from set_task_cpu()
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>
Diffstat (limited to 'kernel/sched.c')
| -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 01fd131b47a4..1f9c6d99f15d 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2060,23 +2060,12 @@ 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 |