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Re: [Qemu-devel] [PATCH 2/2] virtio-blk: use aio handler for data plane
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] virtio-blk: use aio handler for data plane |
Date: |
Tue, 29 Mar 2016 16:58:34 +0300 |
On Tue, Mar 29, 2016 at 03:56:18PM +0200, Paolo Bonzini wrote:
>
>
> On 29/03/2016 15:42, Michael S. Tsirkin wrote:
> > @@ -262,6 +274,7 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
> >
> > /* Stop notifications for new requests from guest */
> > virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx, false,
> > false);
>
> I think that this should have been ", true, false" even before your
> patch; I'd prefer to fix it even if the problem is latent.
Makes sense - post a patch?
> The patch looks good, and it might even be an API improvement
> independent of Conny's patches. The reentrancy _is_ hard to understand,
> and eliminating it makes the new API not just a hack.
>
> In that case I would unify the new function with
> virtio_queue_aio_set_host_notifier_handler. In other words
>
> - virtio_queue_aio_set_host_notifier_handler(vq, ctx, NULL) is
> the same as
>
> virtio_set_queue_aio(s->vq, NULL);
> virtio_queue_aio_set_host_notifier_handler(vq, ctx, true, false);
>
> - virtio_queue_aio_set_host_notifier_handler(vq, ctx, fn) is the same as
>
> virtio_queue_aio_set_host_notifier_handler(vq, ctx, true, true);
> virtio_set_queue_aio(vq, fn);
>
> Thanks,
>
> Paolo
In that case, we'll have to also change scsi to use the new API.
A bit more work, to be sure.
Does scsi have the same problem as blk?
> > + virtio_set_queue_aio(s->vq, NULL);
> >
> > /* Drain and switch bs back to the QEMU main loop */
> > blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context());
Re: [Qemu-devel] [PATCH 0/2] dataplane: fix start/stop races, Michael S. Tsirkin, 2016/03/29
Re: [Qemu-devel] [PATCH 0/2] dataplane: fix start/stop races, Cornelia Huck, 2016/03/29
Re: [Qemu-devel] [PATCH 0/2] dataplane: fix start/stop races, Christian Borntraeger, 2016/03/29