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Re: [Qemu-block] [PATCH 2/3] xen-bus: allow AioContext to be specified f
From: |
Anthony PERARD |
Subject: |
Re: [Qemu-block] [PATCH 2/3] xen-bus: allow AioContext to be specified for each event channel |
Date: |
Wed, 10 Apr 2019 16:22:58 +0100 |
User-agent: |
Mutt/1.11.4 (2019-03-13) |
On Wed, Apr 10, 2019 at 04:20:05PM +0100, Paul Durrant wrote:
> > -----Original Message-----
> > From: Anthony PERARD [mailto:address@hidden
> > Sent: 10 April 2019 13:57
> > To: Paul Durrant <address@hidden>
> > Cc: address@hidden; address@hidden; address@hidden; Stefano Stabellini
> > <address@hidden>; Stefan Hajnoczi <address@hidden>; Kevin Wolf
> > <address@hidden>; Max
> > Reitz <address@hidden>
> > Subject: Re: [PATCH 2/3] xen-bus: allow AioContext to be specified for each
> > event channel
> >
> > On Mon, Apr 08, 2019 at 04:16:16PM +0100, Paul Durrant wrote:
> > > This patch adds an AioContext parameter to xen_device_bind_event_channel()
> > > and then uses aio_set_fd_handler() to set the callback rather than
> > > qemu_set_fd_handler().
> > >
> > > Signed-off-by: Paul Durrant <address@hidden>
> > > ---
> > > @@ -943,6 +944,7 @@ static void xen_device_event(void *opaque)
> > > }
> > >
> > > XenEventChannel *xen_device_bind_event_channel(XenDevice *xendev,
> > > + AioContext *ctx,
> > > unsigned int port,
> > > XenEventHandler handler,
> > > void *opaque, Error
> > > **errp)
> > > @@ -968,8 +970,9 @@ XenEventChannel
> > > *xen_device_bind_event_channel(XenDevice *xendev,
> > > channel->handler = handler;
> > > channel->opaque = opaque;
> > >
> > > - qemu_set_fd_handler(xenevtchn_fd(channel->xeh), xen_device_event,
> > > NULL,
> > > - channel);
> > > + channel->ctx = ctx;
> > > + aio_set_fd_handler(channel->ctx, xenevtchn_fd(channel->xeh), false,
> > > + xen_device_event, NULL, NULL, channel);
> >
> > I wonder if the `'is_external' parameter of aio_set_fd_handler shoud be
> > `true' here, instead. That flag seems to be used when making a snapshot
> > of a blockdev, for example.
> >
> > That was introduced by:
> > dca21ef23ba48f6f1428c59f295a857e5dc203c8^..c07bc2c1658fffeee08eb46402b2f66d55b07586
> >
> > What do you think?
>
> Interesting. I admit I was merely transcribing what qemu_set_fd_handler()
> passes without really looking into the values. Looking at the arguments that
> virtio-blk passes to aio_set_event_notifier() though, and what 'is_external'
> means, it would appear that setting it to true is probably the right thing to
> do. Do you want me to send a v2 of the series or can you fix it up?
I'll fix that up.
Reviewed-by: Anthony PERARD <address@hidden>
Thanks,
--
Anthony PERARD
[Qemu-block] [PATCH 3/3] xen-bus / xen-block: add support for event channel polling, Paul Durrant, 2019/04/08