Messages in this thread | | | Subject | Re: [KVM PATCH v4 3/3] kvm: add iosignalfd support | From | Mark McLoughlin <> | Date | Wed, 27 May 2009 17:25:44 +0000 |
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On Wed, 2009-05-27 at 15:11 +0300, Avi Kivity wrote:
> Multiple cookies on the same address are required by virtio. You can't > mux since the data doesn't go anywhere. > > Virtio can survive by checking all rings on a notify, and we can later > add a mechanism that has a distinct address for each ring, but let's see > if we can cope with multiple cookies. Mark?
Trying to catch up, but you're talking about replacing virtio-pci QUEUE_NOTIFY handling with iosignalfd ?
For a perfect replacement, what you really need is to be able to register multiple cookies per address range, but only have them trigger if the written data matches a provided value.
If the data is lost, virtio has no way of knowing which queue is being notified, so we either end up with per-device, rather than per-queue, notifications (probably not too bad for net, at least) or a different notify address per queue (limiting the number of queues per device).
Cheers, Mark.
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