linux-kernel - Re: [PATCH v16 5/5] virtio-balloon: VIRTIO_BALLOON_F_CTRL

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Date:   Thu, 19 Oct 2017 16:07:06 +0800
From:   Wei Wang <wei.w.wang@...el.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
CC:     "virtio-dev@...ts.oasis-open.org" <virtio-dev@...ts.oasis-open.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
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Subject: Re: [PATCH v16 5/5] virtio-balloon: VIRTIO_BALLOON_F_CTRL_VQ

On 10/13/2017 09:38 PM, Michael S. Tsirkin wrote:
> On Thu, Oct 12, 2017 at 11:54:56AM +0800, Wei Wang wrote:
>>> But I think flushing is very fragile. You will easily run into races
>>> if one of the actors gets out of sync and keeps adding data.
>>> I think adding an ID in the free vq stream is a more robust
>>> approach.
>>>
>> Adding ID to the free vq would need the device to distinguish whether it
>> receives an ID or a free page hint,
> Not really.  It's pretty simple: a 64 bit buffer is an ID. A 4K and bigger one
> is a page.

I think we can also use the previous method, free page via in_buf, and 
id via out_buf.

Best,
Wei