Re: [PATCH] virtio-blk: support polling I/O

From: Suwan Kim <suwan.kim027@gmail.com>
To: Jason Wang <jasowang@redhat.com>
Cc: mst@redhat.com, pbonzini@redhat.com, stefanha@redhat.com,
	virtualization@lists.linux-foundation.org,
	linux-block@vger.kernel.org
Subject: Re: [PATCH] virtio-blk: support polling I/O
Date: Mon, 14 Mar 2022 21:33:08 +0900	[thread overview]
Message-ID: <Yi82BL9KecQsVfgX@localhost.localdomain> (raw)
In-Reply-To: <ea838f63-5f63-6f3b-f49e-1107b43f7d1c@redhat.com>

On Mon, Mar 14, 2022 at 02:14:53PM +0800, Jason Wang wrote:
> 
> 在 2022/3/11 下午11:28, Suwan Kim 写道:
> > diff --git a/include/uapi/linux/virtio_blk.h b/include/uapi/linux/virtio_blk.h
> > index d888f013d9ff..3fcaf937afe1 100644
> > --- a/include/uapi/linux/virtio_blk.h
> > +++ b/include/uapi/linux/virtio_blk.h
> > @@ -119,8 +119,9 @@ struct virtio_blk_config {
> >   	 * deallocation of one or more of the sectors.
> >   	 */
> >   	__u8 write_zeroes_may_unmap;
> > +	__u8 unused1;
> > -	__u8 unused1[3];
> > +	__virtio16 num_poll_queues;
> >   } __attribute__((packed));
> 
> 
> This looks like a implementation specific (virtio-blk-pci) optimization, how
> about other implementation like vhost-user-blk?

I didn’t consider vhost-user-blk yet. But does vhost-user-blk also
use vritio_blk_config as kernel-qemu interface?

Does vhost-user-blk need additional modification to support polling
in kernel side?

Regards,
Suwan Kim