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authorZhang, Yanmin <yanmin_zhang@linux.intel.com>2008-09-08 23:26:33 -0400
committerIngo Molnar <mingo@elte.hu>2008-09-11 03:34:28 -0400
commitbaf25731e54d06eb13dc4eda78c6dc7da4ce84e8 (patch)
treeaf5cbd2b004a2258ebfd332d4871249d1c32f41f
parent291c54ff764d12ecc9a916cb478a0bbb45c5990e (diff)
sched: fix 2.6.27-rc5 couldn't boot on tulsa machine randomly
On my tulsa x86-64 machine, kernel 2.6.25-rc5 couldn't boot randomly. Basically, function __enable_runtime forgets to reset rt_rq->rt_throttled to 0. When every cpu is up, per-cpu migration_thread is created and it runs very fast, sometimes to mark the corresponding rt_rq->rt_throttled to 1 very quickly. After all cpus are up, with below calling chain: sched_init_smp => arch_init_sched_domains => build_sched_domains => ... => cpu_attach_domain => rq_attach_root => set_rq_online => ... => _enable_runtime _enable_runtime is called against every rt_rq again, so rt_rq->rt_time is reset to 0, but rt_rq->rt_throttled might be still 1. Later on function do_sched_rt_period_timer couldn't reset it, and all RT tasks couldn't be scheduled to run on that cpu. here is RT task migration_thread which is woken up when a task is migrated to another cpu. Below patch fixes it against 2.6.27-rc5. Signed-off-by: Zhang Yanmin <yanmin_zhang@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/sched_rt.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 552310798dad..1113157b2058 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -350,6 +350,7 @@ static void __enable_runtime(struct rq *rq)
350 spin_lock(&rt_rq->rt_runtime_lock); 350 spin_lock(&rt_rq->rt_runtime_lock);
351 rt_rq->rt_runtime = rt_b->rt_runtime; 351 rt_rq->rt_runtime = rt_b->rt_runtime;
352 rt_rq->rt_time = 0; 352 rt_rq->rt_time = 0;
353 rt_rq->rt_throttled = 0;
353 spin_unlock(&rt_rq->rt_runtime_lock); 354 spin_unlock(&rt_rq->rt_runtime_lock);
354 spin_unlock(&rt_b->rt_runtime_lock); 355 spin_unlock(&rt_b->rt_runtime_lock);
355 } 356 }