On Tue, Nov 18, 2014 at 10:06 PM, Paolo Bonzini <[email protected]> wrote:
>
>
> On 06/11/2014 16:10, Ming Lei wrote:
>> + /* don't submit until next completion for -EAGAIN of non plug case */
>> + if (unlikely(!s->io_q.plugged)) {
>> + return 0;
>> + }
>> +
>
> Is this an optimization or a fix for something?
It is for avoiding unnecessary submission which will cause
another -EAGAIN.
>
>> + /*
>> + * Switch to queue mode until -EAGAIN is handled, we suppose
>> + * there is always uncompleted I/O, so try to enqueue it first,
>> + * and will be submitted again in following aio completion cb.
>> + */
>> + if (ret == -EAGAIN) {
>> + goto enqueue;
>> + } else if (ret < 0) {
>> goto out_free_aiocb;
>> }
>
> Better:
>
> if (!s->io_q.plugged && !s->io_q.idx) {
> ret = io_submit(s->ctx, 1, &iocbs);
> if (ret >= 0) {
> return &laiocb->common;
> }
> if (ret != -EAGAIN) {
> goto out_free_aiocb;
> }
> }
Right.
Thanks,
Ming Lei
