On Mon, Nov 24, 2014 at 7:38 PM, Paolo Bonzini <pbonz...@redhat.com> wrote:
>
>
> On 24/11/2014 12:31, Ming Lei wrote:
>> + /* don't submit until next completion for -EAGAIN of non plug case */
>> + if (unlikely(!s->io_q.plugged)) {
>> + return 0;
>> + }
>> +
>> /* submit immediately if queue depth is above 2/3 */
>> if (idx > s->io_q.size * 2 / 3) {
>> return ioq_submit(s);
> }
>
> return 0;
>
> so I fail to see why my proposal:
>
>
> /* This is reached in two cases: queue not plugged but io_submit
> * returned -EAGAIN, or queue plugged. In the latter case, start
> * submitting some I/O if the queue is getting too full. In the
> * former case, instead, wait until an I/O operation is completed.
> */
> if (likely(idx <= s->io_q.size * 2 / 3) || unlikely(!s->io_q.plugged) {
> return 0;
> }
>
> return ioq_submit(s);
>
> was wrong. Can you explain?
I didn't say your proposal is wrong, and this patch is correct too
without fat comment.
The difference is only that this patch returns immediately in case
of !s->io_q.plugged after putting the req into io queue.
Thanks,
