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SubjectRe: [PATCH -mm] cpuset,mm: fix no node to alloc memory when changing cpuset's mems - fix2
on 2010-5-12 12:32, Andrew Morton wrote:
> On Wed, 12 May 2010 15:20:51 +0800 Miao Xie <miaox@cn.fujitsu.com> wrote:
>
>> @@ -985,6 +984,7 @@ repeat:
>> * for the read-side.
>> */
>> while (ACCESS_ONCE(tsk->mems_allowed_change_disable)) {
>> + task_unlock(tsk);
>> if (!task_curr(tsk))
>> yield();
>> goto repeat;
>
> Oh, I meant to mention that. No yield()s, please. Their duration is
> highly unpredictable. Can we do something more deterministic here?

Maybe we can use wait_for_completion().

>
> Did you consider doing all this with locking? get_mems_allowed() does
> mutex_lock(current->lock)?

do you means using a real lock(such as: mutex) to protect mempolicy and mem_allowed?

It may cause the performance regression, so I do my best to abstain from using a real
lock.

Thanks
Miao

>
>
>
>




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