From: Paolo Bonzini <pbonzini@redhat.com>
To: Felipe Franciosi <felipe@nutanix.com>,
"Michael S. Tsirkin" <mst@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>,
QEMU Developers <qemu-devel@nongnu.org>
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 [thread overview]
Message-ID: <a819c39f-66e2-8879-0f5f-dce822c8b7d0@redhat.com> (raw)
In-Reply-To: <7A6952CE-E364-4265-A3B9-9BAB7CA620D2@nutanix.com>
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
next prev parent reply other threads:[~2017-06-08 13:33 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-07 15:28 [Qemu-devel] [PULL v5 00/33] Misc patches for 2017-06-01 Paolo Bonzini
2017-06-07 15:28 ` [Qemu-devel] [PULL 18/33] vhost-user-scsi: Introduce vhost-user-scsi host device Paolo Bonzini
2017-06-07 15:37 ` Peter Maydell
2017-06-07 15:39 ` Felipe Franciosi
2017-06-07 15:47 ` Peter Maydell
2017-06-07 18:26 ` Felipe Franciosi
2017-06-07 16:21 ` Paolo Bonzini
2017-06-07 16:26 ` Felipe Franciosi
2017-06-07 18:22 ` Paolo Bonzini
2017-06-07 18:30 ` Michael S. Tsirkin
2017-06-07 18:56 ` Paolo Bonzini
2017-06-08 0:31 ` Michael S. Tsirkin
2017-06-08 11:05 ` Felipe Franciosi
2017-06-08 13:33 ` Paolo Bonzini [this message]
-- strict thread matches above, loose matches on Subject: below --
2017-06-07 13:55 [Qemu-devel] [PULL v4 00/33] Misc patches for 2017-06-01 Paolo Bonzini
2017-06-07 13:55 ` [Qemu-devel] [PULL 18/33] vhost-user-scsi: Introduce vhost-user-scsi host device Paolo Bonzini
2017-06-06 14:02 [Qemu-devel] [PULL v3 00/33] Misc patches for 2017-06-01 Paolo Bonzini
2017-06-06 14:02 ` [Qemu-devel] [PULL 18/33] vhost-user-scsi: Introduce vhost-user-scsi host device Paolo Bonzini
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