Re: [PATCH] virtio-ring: Use threshold for switching to indirectdescriptors

From: Sasha Levin
Date: Sun Dec 04 2011 - 12:39:52 EST


On Sun, 2011-12-04 at 19:37 +0200, Avi Kivity wrote:
> On 12/04/2011 07:34 PM, Sasha Levin wrote:
> > >
> > > I'm confused. didn't you see a bigger benefit for guest->host by
> > > switching indirect off?
> >
> > The 5% improvement is over the 'regular' indirect on, not over indirect
> > off. Sorry for the confusion there.
> >
> > I suggested this change regardless of the outcome of indirect descriptor
> > threshold discussion, since it would help anyways.
>
> For net, this makes sense. For block, it reduces the effective queue
> depth, so it's not a trivial change. It probably makes sense there too,
> though.

It doesn't have to be limited at that number, anything above that can go
through the regular kmalloc() path.

--

Sasha.

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