On 02/09/2015 04:50 PM, Peter Zijlstra wrote:
> On Mon, Feb 09, 2015 at 08:05:57PM +0000, Jason Baron wrote:
>> diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
>> index 852143a..17d1039 100644
>> --- a/kernel/sched/wait.c
>> +++ b/kernel/sched/wait.c
>> @@ -71,8 +71,11 @@ static void __wake_up_common(wait_queue_head_t *q,
>> unsigned int mode,
>> unsigned flags = curr->flags;
>>
>> if (curr->func(curr, mode, wake_flags, key) &&
>> - (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
>> + (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive) {
>> + if (flags & WQ_FLAG_ROUND_ROBIN)
>> + list_move_tail(&curr->task_list, &q->task_list);
>> break;
>> + }
>> }
>> }
> I think you meant to write something like:
>
> if (curr->func(curr, mode, wake_flags, key) &&
> (flags & WQ_FLAG_EXCLUSIVE)) {
> if (flag & WQ_FLAG_ROUND_ROBIN)
> list_move_tail(&curr->task_list, &q->task_list);
> if (!--nr_exclusive)
> break;
> }
>
> Otherwise can only work for nr_exclusive==1.
Indeed. I'm also wondering if its worth avoiding the list_move_tail() for the
case where nr_exclusive is initially 0. IE the wake all case, where we are just
going to end up doing a bunch of list_move_tail() calls, but end up in the same
state.
Thanks,
-Jason
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