From 1799e35d5baab6e06168b46cc78b968e728ea3d1 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Wed, 19 Sep 2007 23:34:46 +0200 Subject: sched: add /proc/sys/kernel/sched_compat_yield add /proc/sys/kernel/sched_compat_yield to make sys_sched_yield() more agressive, by moving the yielding task to the last position in the rbtree. with sched_compat_yield=0: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2539 mingo 20 0 1576 252 204 R 50 0.0 0:02.03 loop_yield 2541 mingo 20 0 1576 244 196 R 50 0.0 0:02.05 loop with sched_compat_yield=1: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2584 mingo 20 0 1576 248 196 R 99 0.0 0:52.45 loop 2582 mingo 20 0 1576 256 204 R 0 0.0 0:00.00 loop_yield Signed-off-by: Ingo Molnar Signed-off-by: Peter Zijlstra --- kernel/sched.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'kernel/sched.c') diff --git a/kernel/sched.c b/kernel/sched.c index deeb1f8e0c30..63e0971c8fbb 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4550,10 +4550,7 @@ asmlinkage long sys_sched_yield(void) struct rq *rq = this_rq_lock(); schedstat_inc(rq, yld_cnt); - if (unlikely(rq->nr_running == 1)) - schedstat_inc(rq, yld_act_empty); - else - current->sched_class->yield_task(rq, current); + current->sched_class->yield_task(rq, current); /* * Since we are going to call schedule() anyway, there's -- cgit v1.2.2 From 9c95e7319ba98585ebb6d304eca2d56f401ed70c Mon Sep 17 00:00:00 2001 From: Hiroshi Shimamoto Date: Wed, 19 Sep 2007 23:34:46 +0200 Subject: sched: fix invalid sched_class use When using rt_mutex, a NULL pointer dereference is occurred at enqueue_task_rt. Here is a scenario; 1) there are two threads, the thread A is fair_sched_class and thread B is rt_sched_class. 2) Thread A is boosted up to rt_sched_class, because the thread A has a rt_mutex lock and the thread B is waiting the lock. 3) At this time, when thread A create a new thread C, the thread C has a rt_sched_class. 4) When doing wake_up_new_task() for the thread C, the priority of the thread C is out of the RT priority range, because the normal priority of thread A is not the RT priority. It makes data corruption by overflowing the rt_prio_array. The new thread C should be fair_sched_class. The new thread should be valid scheduler class before queuing. This patch fixes to set the suitable scheduler class. Signed-off-by: Hiroshi Shimamoto Signed-off-by: Ingo Molnar Signed-off-by: Peter Zijlstra --- kernel/sched.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'kernel/sched.c') diff --git a/kernel/sched.c b/kernel/sched.c index 63e0971c8fbb..6107a0cd6325 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -1682,6 +1682,11 @@ void fastcall wake_up_new_task(struct task_struct *p, unsigned long clone_flags) p->prio = effective_prio(p); + if (rt_prio(p->prio)) + p->sched_class = &rt_sched_class; + else + p->sched_class = &fair_sched_class; + if (!p->sched_class->task_new || !sysctl_sched_child_runs_first || (clone_flags & CLONE_VM) || task_cpu(p) != this_cpu || !current->se.on_rq) { -- cgit v1.2.2