Il 30/07/2014 13:39, Ming Lei ha scritto: > In the enqueue path, we can't complete request, otherwise > "Co-routine re-entered recursively" may be caused, so this > patch fixes the issue with below ideas: > > - for -EAGAIN or partial completion, retry the submission by > an introduced event handler > - for part of completion, also update the io queue > - for other failure, return the failure if in enqueue path, > otherwise, abort all queued I/O > > Signed-off-by: Ming Lei <ming....@canonical.com> > --- > block/linux-aio.c | 90 > ++++++++++++++++++++++++++++++++++++++++------------- > 1 file changed, 68 insertions(+), 22 deletions(-) > > diff --git a/block/linux-aio.c b/block/linux-aio.c > index 7ac7e8c..5eb9c92 100644 > --- a/block/linux-aio.c > +++ b/block/linux-aio.c > @@ -51,6 +51,7 @@ struct qemu_laio_state { > > /* io queue for submit at batch */ > LaioQueue io_q; > + EventNotifier retry; /* handle -EAGAIN and partial completion */ > }; > > static inline ssize_t io_event_ret(struct io_event *ev) > @@ -154,45 +155,80 @@ static void ioq_init(LaioQueue *io_q) > io_q->plugged = 0; > } > > -static int ioq_submit(struct qemu_laio_state *s) > +static void abort_queue(struct qemu_laio_state *s) > +{ > + int i; > + for (i = 0; i < s->io_q.idx; i++) { > + struct qemu_laiocb *laiocb = container_of(s->io_q.iocbs[i], > + struct qemu_laiocb, > + iocb); > + laiocb->ret = -EIO; > + qemu_laio_process_completion(s, laiocb); > + } > +} > + > +static int ioq_submit(struct qemu_laio_state *s, bool enqueue) > { > int ret, i = 0; > int len = s->io_q.idx; > + int j = 0; > > - do { > - ret = io_submit(s->ctx, len, s->io_q.iocbs); > - } while (i++ < 3 && ret == -EAGAIN); > + if (!len) { > + return 0; > + } > > - /* empty io queue */ > - s->io_q.idx = 0; > + ret = io_submit(s->ctx, len, s->io_q.iocbs); > + if (ret == -EAGAIN) { > + event_notifier_set(&s->retry);
Retrying immediately (and just doing a couple of system calls to waste time) is not an improvement. The right place to retry is in qemu_laio_completion_cb, after io_getevents has been called and presumably the queue depth has decreased. If !s->io_q.plugged but io_submit fails you can call ioq_enqueue and it will just work. Then you can only go to out_free_aiocb if the queue is full (independent of the "plug" state). Paolo > + return 0; > + } else if (ret < 0) { > + if (enqueue) { > + return ret; > + } > > - if (ret < 0) { > - i = 0; > - } else { > - i = ret; > + /* in non-queue path, all IOs have to be completed */ > + abort_queue(s); > + ret = len; > + } else if (ret == 0) { > + goto out; > } > > - for (; i < len; i++) { > - struct qemu_laiocb *laiocb = > - container_of(s->io_q.iocbs[i], struct qemu_laiocb, iocb); > - > - laiocb->ret = (ret < 0) ? ret : -EIO; > - qemu_laio_process_completion(s, laiocb); > + for (i = ret; i < len; i++) { > + s->io_q.iocbs[j++] = s->io_q.iocbs[i]; > } > + > + out: > + /* update io queue */ > + s->io_q.idx -= ret; > + > return ret; > } > > -static void ioq_enqueue(struct qemu_laio_state *s, struct iocb *iocb) > +static void ioq_submit_retry(EventNotifier *e) > +{ > + struct qemu_laio_state *s = container_of(e, struct qemu_laio_state, > retry); > + > + event_notifier_test_and_clear(e); > + ioq_submit(s, false); > +} > + > +static int ioq_enqueue(struct qemu_laio_state *s, struct iocb *iocb) > { > unsigned int idx = s->io_q.idx; > > + if (unlikely(idx == s->io_q.size)) { > + return -1; > + } > + > s->io_q.iocbs[idx++] = iocb; > s->io_q.idx = idx; > > - /* submit immediately if queue is full */ > - if (idx == s->io_q.size) { > - ioq_submit(s); > + /* submit immediately if queue depth is above 2/3 */ > + if (idx > s->io_q.size * 2 / 3) { > + return ioq_submit(s, true); > } > + > + return 0; > } > > void laio_io_plug(BlockDriverState *bs, void *aio_ctx) > @@ -214,7 +250,7 @@ int laio_io_unplug(BlockDriverState *bs, void *aio_ctx, > bool unplug) > } > > if (s->io_q.idx > 0) { > - ret = ioq_submit(s); > + ret = ioq_submit(s, false); > } > > return ret; > @@ -258,7 +294,9 @@ BlockDriverAIOCB *laio_submit(BlockDriverState *bs, void > *aio_ctx, int fd, > goto out_free_aiocb; > } > } else { > - ioq_enqueue(s, iocbs); > + if (ioq_enqueue(s, iocbs) < 0) { > + goto out_free_aiocb; > + } > } > return &laiocb->common; > > @@ -272,6 +310,7 @@ void laio_detach_aio_context(void *s_, AioContext > *old_context) > struct qemu_laio_state *s = s_; > > aio_set_event_notifier(old_context, &s->e, NULL); > + aio_set_event_notifier(old_context, &s->retry, NULL); > } > > void laio_attach_aio_context(void *s_, AioContext *new_context) > @@ -279,6 +318,7 @@ void laio_attach_aio_context(void *s_, AioContext > *new_context) > struct qemu_laio_state *s = s_; > > aio_set_event_notifier(new_context, &s->e, qemu_laio_completion_cb); > + aio_set_event_notifier(new_context, &s->retry, ioq_submit_retry); > } > > void *laio_init(void) > @@ -295,9 +335,14 @@ void *laio_init(void) > } > > ioq_init(&s->io_q); > + if (event_notifier_init(&s->retry, false) < 0) { > + goto out_notifer_init; > + } > > return s; > > +out_notifer_init: > + io_destroy(s->ctx); > out_close_efd: > event_notifier_cleanup(&s->e); > out_free_state: > @@ -310,6 +355,7 @@ void laio_cleanup(void *s_) > struct qemu_laio_state *s = s_; > > event_notifier_cleanup(&s->e); > + event_notifier_cleanup(&s->retry); > > if (io_destroy(s->ctx) != 0) { > fprintf(stderr, "%s: destroy AIO context %p failed\n", >