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Date: Thu, 19 Nov 2009 17:19:34 +0200
From: Avi Kivity <avi@redhat.com>
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Subject: [Qemu-devel] Re: virtio: Report new guest memory statistics
 pertinent to memory ballooning (V4)
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To: Adam Litke <agl@us.ibm.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, qemu-devel@nongnu.org

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.

> 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.

> -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.

> +    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.


-- 
error compiling committee.c: too many arguments to function