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[Qemu-devel] Re: virtio: Report new guest memory statistics pertinent to
From: |
Adam Litke |
Subject: |
[Qemu-devel] Re: virtio: Report new guest memory statistics pertinent to memory ballooning (V4) |
Date: |
Thu, 19 Nov 2009 09:56:31 -0600 |
On Thu, 2009-11-19 at 17:19 +0200, Avi Kivity wrote:
> On 11/19/2009 05:06 PM, Adam Litke wrote:
> > Avi and Anthony,
> > If you agree that I've addressed all outstanding issues, please consider
> > this
> > patch for inclusion. Thanks.
> >
> >
>
> I'd like to see this (and all other virtio-ABI-modifying patches) first
> go into the virtio pci spec, then propagated to guest and host.
Where can I find information on the procedure for updating the virtio
pci spec?
> > Changes since V3:
> > - Increase stat field size to 64 bits
> > - Report all sizes in kb (not pages)
> >
>
> Why not bytes? It's the most natural unit.
The precision for most of these stats (except major and minor faults)
is 4kb (at least for Linux guests on the platforms I can think of). I
chose kb units to avoid wasting bits. I suppose the 64bit fields are
"Bigger than we could ever possibly need (tm)". Others have suggested
bytes as well so I will be happy to make the change.
> > -static ram_addr_t virtio_balloon_to_target(void *opaque, ram_addr_t target)
> > +static void request_stats(VirtIOBalloon *vb)
> > +{
> > + vb->stats_requested = 1;
> > + reset_stats(vb);
> > + monitor_suspend(cur_mon);
> >
>
> You allow the guest to kill a monitor here.
Is there a better way to handle asynchronous communication with the
guest?
> > + virtqueue_push(vb->svq,&vb->stats_vq_elem, vb->stats_vq_offset);
> > + virtio_notify(&vb->vdev, vb->svq);
> > +}
> > +
> >
>
>
>
> > +typedef struct VirtIOBalloonStat {
> > + uint16_t tag;
> > + uint64_t val;
> > +} VirtIOBalloonStat;
> >
>
> Alignment here depends on word size. This needs to be padded to be
> aligned the same way on 32 and 64 bit hosts and guests.
ok. I assume that means the structure size must be a multiple of 64
bits in size?
--
Thanks,
Adam
[Qemu-devel] Re: virtio: Report new guest memory statistics pertinent to memory ballooning (V4), Avi Kivity, 2009/11/19