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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: qemu-devel@nongnu.org, Doug Goldstein <cardoe@cardoe.com>,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 2/2] virtio: disable notifications again after poll succeeded
Date: Fri, 13 Jan 2017 17:53:05 +0200	[thread overview]
Message-ID: <20170113175234-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20170112114612.14520-3-stefanha@redhat.com>

On Thu, Jan 12, 2017 at 11:46:11AM +0000, Stefan Hajnoczi wrote:
> While AioContext is in polling mode virtqueue notifications are not
> necessary.  Some device virtqueue handlers enable notifications.  Make
> sure they stay disabled to avoid unnecessary vmexits.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

So I'll put just the revert in today's pull request,
let's make sure this one is not causing regressions.

> ---
>  hw/virtio/virtio.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index f04ab7a..34065c7 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -2126,6 +2126,9 @@ static bool virtio_queue_host_notifier_aio_poll(void *opaque)
>      }
>  
>      virtio_queue_notify_aio_vq(vq);
> +
> +    /* In case the handler function re-enabled notifications */
> +    virtio_queue_set_notification(vq, 0);
>      return true;
>  }
>  
> -- 
> 2.9.3

  reply	other threads:[~2017-01-13 15:53 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-12 11:46 [Qemu-devel] [PATCH 0/2] virtio: revert virtio_queue_set_notification() nesting Stefan Hajnoczi
2017-01-12 11:46 ` [Qemu-devel] [PATCH 1/2] Revert "virtio: turn vq->notification into a nested counter" Stefan Hajnoczi
2017-01-12 11:46 ` [Qemu-devel] [PATCH 2/2] virtio: disable notifications again after poll succeeded Stefan Hajnoczi
2017-01-13 15:53   ` Michael S. Tsirkin [this message]
2017-01-12 16:57 ` [Qemu-devel] [PATCH 0/2] virtio: revert virtio_queue_set_notification() nesting Doug Goldstein
2017-01-12 20:05   ` Michael S. Tsirkin
2017-01-13 14:48     ` Doug Goldstein
2017-01-13 12:02   ` Stefan Hajnoczi
2017-01-13 15:15     ` Doug Goldstein
2017-01-16 10:46       ` Stefan Hajnoczi
2017-01-16 21:03         ` Doug Goldstein
2017-01-17  3:09           ` Michael S. Tsirkin
2017-01-17  9:49           ` Stefan Hajnoczi
2017-01-14  3:48 ` Richard Henderson
2017-01-16 23:31 ` Laszlo Ersek

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