Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself

[Avi Kivity]

On 05/05/2010 11:58 PM, Michael S. Tsirkin wrote:
> +       /* We publish the last-seen used index at the end of the available ring.
> +        * It is at the end for backwards compatibility. */
> +       vr->last_used_idx =&(vr)->avail->ring[num];
> +       /* Verify that last used index does not spill over the used ring. */
> +       BUG_ON((void *)vr->last_used_idx +
> +              sizeof *vr->last_used_idx>  (void *)vr->used);
>   }
>    

Shouldn't this be on its own cache line?

One way to achieve this is to allocate it at the end.

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error compiling committee.c: too many arguments to function