Re: [PATCH 3/3] linux-aio: limit the batch size using `aio-max-batch` parameter

[Stefan Hajnoczi]

On Wed, Jul 07, 2021 at 05:00:19PM +0200, Stefano Garzarella wrote:
> @@ -371,7 +375,7 @@ static int laio_do_submit(int fd, struct qemu_laiocb 
> *laiocb, off_t offset,
>      s->io_q.in_queue++;
>      if (!s->io_q.blocked &&
>          (!s->io_q.plugged ||
> -         s->io_q.in_flight + s->io_q.in_queue >= MAX_EVENTS)) {
> +         s->io_q.in_queue >= max_batch)) {

Is it safe to drop the MAX_EVENTS case?

Perhaps the following can be used:

  int64_t max_batch = s->aio_context->aio_max_batch ?: DEFAULT_MAX_BATCH;
  max_batch = MIN_NON_ZERO(MAX_EVENTS - s->io_q.in_flight + s->io_q.in_queue, 
max_batch);

Here we'll only need to check against max_batch but it takes into
account MAX_EVENT and in_flight.

Stefan

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