sched: Drop rq->lock from sched_exec()
Since we can now call select_task_rq() and set_task_cpu() with only
p->pi_lock held, and sched_exec() load-balancing has always been
optimistic, drop all rq->lock usage.
Oleg also noted that need_migrate_task() will always be true for
current, so don't bother calling that at all.
Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110405152729.314204889@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched.c b/kernel/sched.c
index 7c5494d..1be1a09 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3465,27 +3465,22 @@
{
struct task_struct *p = current;
unsigned long flags;
- struct rq *rq;
int dest_cpu;
- rq = task_rq_lock(p, &flags);
+ raw_spin_lock_irqsave(&p->pi_lock, flags);
dest_cpu = p->sched_class->select_task_rq(p, SD_BALANCE_EXEC, 0);
if (dest_cpu == smp_processor_id())
goto unlock;
- /*
- * select_task_rq() can race against ->cpus_allowed
- */
- if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed) &&
- likely(cpu_active(dest_cpu)) && need_migrate_task(p)) {
+ if (likely(cpu_active(dest_cpu))) {
struct migration_arg arg = { p, dest_cpu };
- task_rq_unlock(rq, p, &flags);
- stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
+ raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+ stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
return;
}
unlock:
- task_rq_unlock(rq, p, &flags);
+ raw_spin_unlock_irqrestore(&p->pi_lock, flags);
}
#endif