Commit 79b3feff authored Feb 18, 2008 by Peter Zijlstra Committed by Ingo Molnar Apr 19, 2008

sched: fix regression with sched yield



Balbir Singh reported:

> 1:mon> t
> [c0000000e7677da0] c000000000067de0 .sys_sched_yield+0x6c/0xbc
> [c0000000e7677e30] c000000000008748 syscall_exit+0x0/0x40
> --- Exception: c01 (System Call) at 00000400001d09e4
> SP (4000664cb10) is in userspace
> 1:mon> r
> cpu 0x1: Vector: 300 (Data Access) at [c0000000e7677aa0]
>     pc: c000000000068e50: .yield_task_fair+0x94/0xc4
>     lr: c000000000067de0: .sys_sched_yield+0x6c/0xbc

the check that should have avoided that is:

        /*
         * Are we the only task in the tree?
         */
        if (unlikely(rq->load.weight == curr->se.load.weight))
                return;

But I guess that overlooks rt tasks, they also increase the load.
So I guess something like this ought to fix it..

Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 19fb518c

kernel/sched_fair.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -904,7 +904,7 @@ static void yield_task_fair(struct rq *rq)
		/*
		* Already in the rightmost position?
		*/
		if (unlikely(rightmost->vruntime < se->vruntime))
		if (unlikely(!rightmost \|\| rightmost->vruntime < se->vruntime))
		return;

		/*