Re: [PATCHv2-RFC 0/2] virtio: put last seen used index into ring itself

[Rusty Russell]

On Thu, 27 May 2010 05:20:35 am Michael S. Tsirkin wrote:
> Here's a rewrite of the original patch with a new layout.
> I haven't tested it yet so no idea how this performs, but
> I think this addresses the cache bounce issue raised by Avi.
> Posting for early flames/comments.

Sorry, not without some evidence that it'll actually reduce cacheline
bouncing.  I *think* it will, but it's not obvious: the host may keep
looking at avail_idx as we're updating last_seen.  Or does qemu always
look at both together anyway?

Can someone convince me this is a win?
Rusty.
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