Re: [patch] sched-sync-2.5.69-A0

Mike Galbraith (efault@gmx.de)
Wed, 21 May 2003 11:08:34 +0200


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At 10:35 AM 5/19/2003 +0200, Ingo Molnar wrote:

>the attached patch fixes the scheduler's sync-wakeup code to be consistent
>on UP as well.
>
>Right now there's a behavioral difference between an UP kernel and an SMP
>kernel running on a UP box: sync wakeups (which are only activated on SMP)
>can cause a wakeup of a higher prio task, without preemption. On UP
>kernels this does not happen. This difference in wakeup behavior is bad.

Cool. That was the cause of some of the radical differences in behavior
between smp and up kernels. The sync wakeup in pipe wait for example was
the irman process load climbs through the roof problem, and it also affects
the ext3 concurrency problem if you have gcc using -pipe. See attached log.

-Mike
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