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Re: [Qemu-devel] [PULL 18/33] vhost-user-scsi: Introduce vhost-user-scsi
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PULL 18/33] vhost-user-scsi: Introduce vhost-user-scsi host device |
Date: |
Thu, 8 Jun 2017 15:33:03 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.0 |
On 08/06/2017 13:05, Felipe Franciosi wrote:
>> Weird. Doesn't QEMU wait for response to GET_VRING_BASE? I think
>> it does since we migrate the returned value.
>
> It does and that's what I said on my first message. On
> GET_VRING_BASE, a vhost-user-scsi backend application will stop
> picking up new requests and, _additionally_, quiesce the VQ (by
> waiting for any outstanding I/O to complete or cancelling them)
> before returning the last_avail_idx.
Yes, I understand now.
> Such an application therefore doesn't _necessarily_ need a drain
> call. However, we could extend vhost-user to include a message for
> draining (which can be implemented as "wait for pending I/O to
> complete" or "cancel all outstanding" depending on the
> implementation).
Ok, and I see that vhost_dev_stop also calls get_vring_base so my
worries are appeased. :)
Paolo
- Re: [Qemu-devel] [PULL 18/33] vhost-user-scsi: Introduce vhost-user-scsi host device, (continued)
- Re: [Qemu-devel] [PULL 18/33] vhost-user-scsi: Introduce vhost-user-scsi host device, Paolo Bonzini, 2017/06/07
- Re: [Qemu-devel] [PULL 18/33] vhost-user-scsi: Introduce vhost-user-scsi host device, Felipe Franciosi, 2017/06/07
- Re: [Qemu-devel] [PULL 18/33] vhost-user-scsi: Introduce vhost-user-scsi host device, Paolo Bonzini, 2017/06/07
- Re: [Qemu-devel] [PULL 18/33] vhost-user-scsi: Introduce vhost-user-scsi host device, Michael S. Tsirkin, 2017/06/07
- Re: [Qemu-devel] [PULL 18/33] vhost-user-scsi: Introduce vhost-user-scsi host device, Paolo Bonzini, 2017/06/07
- Re: [Qemu-devel] [PULL 18/33] vhost-user-scsi: Introduce vhost-user-scsi host device, Michael S. Tsirkin, 2017/06/07
- Re: [Qemu-devel] [PULL 18/33] vhost-user-scsi: Introduce vhost-user-scsi host device, Felipe Franciosi, 2017/06/08
- Re: [Qemu-devel] [PULL 18/33] vhost-user-scsi: Introduce vhost-user-scsi host device,
Paolo Bonzini <=