Re: [Xen-devel] [PATCH RFC] xenbus_client: extend interface to suppurt multi-page ring

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, Aug 20, 2013 at 06:41:29PM +0100, Wei Liu wrote:
> On Tue, Aug 20, 2013 at 6:11 PM, Konrad Rzeszutek Wilk
> <konrad.wilk@xxxxxxxxxx> wrote:
> > On Thu, May 30, 2013 at 03:09:12PM +0100, Wei Liu wrote:
> >> On Thu, May 30, 2013 at 03:06:00PM +0100, Wei Liu wrote:
> >> > Originally Xen PV drivers only use single-page ring to pass along
> >> > information. This might limit the throughput between frontend and
> >> > backend as they can easily run out of ring slots if hardware is fast.
> >> >
> >> > The patch extends Xenbus driver to support multi-page ring, which in
> >> > general should improve throughput. Changes to various frontend / backend
> >> > to adapt to the new interface are also included.
> >> >
> >> > Affected Xen drivers:
> >> > * blkfront/back
> >> > * netfront/back
> >> > * pcifront/back
> >> >
> >> > The interface is documented, as before, in xenbus_client.c.
> >> >
> >>
> >> Please note that this patch won't apply cleanly on upstream kernel as it
> >> relies on some patches that are not in tree.
> >
> > OK.
> >>
> >> I mainly want to collect views on the interface.  Also in the HVM case I
> >> use vmap, I would like to know if I get it right.
> >
> > This patches looks familiar that I had seen some time ago (maybe I even
> > backported it for PV?). Anyhow the PV part looks OK.
> >
> > The HVM - I don't see why we cannot do vmap. The nature of the ring is that
> > it stays mapped for a very long time - so using vmap is OK. That is, the
> > issues with vmap is that it takes a bit to setup and teardown - and that
> > is OK with us.
> >
> > If you would like to rebase it on top of v3.11-rc5 and repost it I don't
> > see why we can't have it for v3.12. David, Boris?
> >
> 
> I think the above implementation has a problem in the HVM case, but I
> cannot recall what. :-(

Heh. Well does it work?
> 
> If you're generally happy with the idea, I can polish this patch and
> target it for 3.12.

Yes sure. We still have some time before I need to clamp down.
> 
> Wei.
> 
> >>
> >>
> >> Thanks
> >> Wei.
> >>
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> >>
> >
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> > http://lists.xen.org/xen-devel

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