[virtio-dev] Re: [virtio-comment] [PATCH 0/5] virtio: introduce SUSPEND bit and vq state

["Zhu, Lingshan" <lingshan.zhu@intel.com>]

On 9/6/2023 9:49 PM, Michael S. Tsirkin wrote:
> On Wed, Sep 06, 2023 at 04:38:44PM +0800, Zhu, Lingshan wrote:
>>
>> On 9/6/2023 4:29 PM, Michael S. Tsirkin wrote:
>>> On Wed, Sep 06, 2023 at 04:16:32PM +0800, Zhu Lingshan wrote:
>>>> This series introduces
>>>> 1)a new SUSPEND bit in the device status
>>>> Which is used to suspend the device, so that the device states
>>>> and virtqueue states are stabilized.
>>>>
>>>> 2)virtqueue state and its accessor, to get and set last_avail_idx
>>>> and last_used_idx of virtqueues.
>>>>
>>>> The main usecase of these new facilities is Live Migration.
>>>>
>>>> Future work: dirty page tracking and in-flight descriptors.
>>> oh that answers my question - it's not covered.
>>> I don't think we can merge this without in-flight descriptor
>>> support.
>> When SUSPEND, we require the device wait until all descriptors that
>> being processed to finish and mark them as used.(In patch 2)
>> at this point there may be no in-flight descriptors, so this is still
>> self-consistent. The tracker for in-flight descriptors is excluded to
>> make this series small and focus.
> Does not work generally.
> Imagine RX ring of a network device for example. You can wait
> as long as you can but if there's no incoming network traffic
> buffers will not be used.
Yes we will include a patch tracking in-flight descriptors in V2.
>
> Also please, keep to the spec terminology. buffers are used not
> descriptors. Best to keep it straight errors will not leak into
> spec.
OK
>
>
>>>
>>>
>>>> This series addresses many comments from Jason, Stefan and Eugenio
>>>> from RFC series.
>>>>
>>>> Zhu Lingshan (5):
>>>>     virtio: introduce vq state as basic facility
>>>>     virtio: introduce SUSPEND bit in device status
>>>>     virtqueue: constraints for virtqueue state
>>>>     virtqueue: ignore resetting vqs when SUSPEND
>>>>     virtio-pci: implement VIRTIO_F_QUEUE_STATE
>>>>
>>>>    content.tex       | 118 ++++++++++++++++++++++++++++++++++++++++++++++
>>>>    transport-pci.tex |  18 +++++++
>>>>    2 files changed, 136 insertions(+)
>>>>
>>>> -- 
>>>> 2.35.3
>>>>
>>>>
>>>> This publicly archived list offers a means to provide input to the
>>>> OASIS Virtual I/O Device (VIRTIO) TC.
>>>>
>>>> In order to verify user consent to the Feedback License terms and
>>>> to minimize spam in the list archive, subscription is required
>>>> before posting.
>>>>
>>>> Subscribe: virtio-comment-subscribe@lists.oasis-open.org
>>>> Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org
>>>> List help: virtio-comment-help@lists.oasis-open.org
>>>> List archive: https://lists.oasis-open.org/archives/virtio-comment/
>>>> Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf
>>>> List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists
>>>> Committee: https://www.oasis-open.org/committees/virtio/
>>>> Join OASIS: https://www.oasis-open.org/join/
>>>>


---------------------------------------------------------------------
To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org
For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org