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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2009-01-14 15:36:26 +0100
committerIngo Molnar <mingo@elte.hu>2009-01-14 18:09:00 +0100
commit41719b03091911028116155deddc5eedf8c45e37 (patch)
tree20a699807d78bc0af86b19443dc751415c0cc6f7 /kernel/sched.c
parent93d81d1aca26e64a75d06a85f7e128b5f49053e7 (diff)
downloadlwn-41719b03091911028116155deddc5eedf8c45e37.tar.gz
lwn-41719b03091911028116155deddc5eedf8c45e37.zip
mutex: preemption fixes
The problem is that dropping the spinlock right before schedule is a voluntary preemption point and can cause a schedule, right after which we schedule again. Fix this inefficiency by keeping preemption disabled until we schedule, do this by explicity disabling preemption and providing a schedule() variant that assumes preemption is already disabled. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r--kernel/sched.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 8be2c13b50d0..b001c133c359 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4538,15 +4538,13 @@ pick_next_task(struct rq *rq, struct task_struct *prev)
/*
* schedule() is the main scheduler function.
*/
-asmlinkage void __sched schedule(void)
+asmlinkage void __sched __schedule(void)
{
struct task_struct *prev, *next;
unsigned long *switch_count;
struct rq *rq;
int cpu;
-need_resched:
- preempt_disable();
cpu = smp_processor_id();
rq = cpu_rq(cpu);
rcu_qsctr_inc(cpu);
@@ -4603,7 +4601,13 @@ need_resched_nonpreemptible:
if (unlikely(reacquire_kernel_lock(current) < 0))
goto need_resched_nonpreemptible;
+}
+asmlinkage void __sched schedule(void)
+{
+need_resched:
+ preempt_disable();
+ __schedule();
preempt_enable_no_resched();
if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
goto need_resched;