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

From: Avi Kivity
Date: Thu May 06 2010 - 06:00:48 EST


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.

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

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