Am 26.11.2014 um 15:46 hat Kevin Wolf geschrieben:
> When getting an error while submitting requests, we must be careful to
> wake up only inactive coroutines. Therefore we must special-case the
> currently active coroutine and communicate an error for that request
> using the ordinary return value of ioq_submit().
>
> Signed-off-by: Kevin Wolf <kw...@redhat.com>
> ---
> block/linux-aio.c | 23 ++++++++++++++++-------
> 1 file changed, 16 insertions(+), 7 deletions(-)
Ming, did you have a look at this patch specifically? Does it fix the
issue that you tried to address with a much more complex callback-based
patch?
I'd like to go forward with this as both Peter and I have measured
considerable performance improvements with our optimisation proposals,
and this series is an important part of it.
Kevin
> diff --git a/block/linux-aio.c b/block/linux-aio.c
> index 99b259d..fd8f0e4 100644
> --- a/block/linux-aio.c
> +++ b/block/linux-aio.c
> @@ -177,12 +177,19 @@ static int ioq_submit(struct qemu_laio_state *s)
> container_of(s->io_q.iocbs[i], struct qemu_laiocb, iocb);
>
> laiocb->ret = (ret < 0) ? ret : -EIO;
> - qemu_laio_process_completion(s, laiocb);
> + if (laiocb->co != qemu_coroutine_self()) {
> + qemu_coroutine_enter(laiocb->co, NULL);
> + } else {
> + /* The return value is used for the currently active coroutine.
> + * We're always in ioq_enqueue() here, ioq_submit() never runs
> from
> + * a request's coroutine.*/
> + ret = laiocb->ret;
> + }
> }
> return ret;
> }
>
> -static void ioq_enqueue(struct qemu_laio_state *s, struct iocb *iocb)
> +static int ioq_enqueue(struct qemu_laio_state *s, struct iocb *iocb)
> {
> unsigned int idx = s->io_q.idx;
>
> @@ -191,7 +198,9 @@ static void ioq_enqueue(struct qemu_laio_state *s, struct
> iocb *iocb)
>
> /* submit immediately if queue is full */
> if (idx == s->io_q.size) {
> - ioq_submit(s);
> + return ioq_submit(s);
> + } else {
> + return 0;
> }
> }
>
> @@ -253,11 +262,11 @@ int laio_submit_co(BlockDriverState *bs, void *aio_ctx,
> int fd,
>
> if (!s->io_q.plugged) {
> ret = io_submit(s->ctx, 1, &iocbs);
> - if (ret < 0) {
> - return ret;
> - }
> } else {
> - ioq_enqueue(s, iocbs);
> + ret = ioq_enqueue(s, iocbs);
> + }
> + if (ret < 0) {
> + return ret;
> }
>
> qemu_coroutine_yield();
> --
> 1.8.3.1
>
