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

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Aug 27, 2013 at 09:23:24AM +0100, Ian Campbell wrote:
> On Fri, 2013-08-23 at 23:27 +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.
> > 
> > The patch extends Xenbus driver to support multi-page ring, which in
> > general should improve throughput if ring is the bottleneck. Changes to
> > various frontend / backend to adapt to the new interface are also
> > included.
> 
> The changes to the front/backends here simply adapt to the new interface
> but don't actually make use of it, right?
> 

No, they don't.

> > @@ -196,15 +200,18 @@ int xenbus_watch_pathfmt(struct xenbus_device *dev, 
> > struct xenbus_watch *watch,
> >                      const char *pathfmt, ...);
> >  
> >  int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state 
> > new_state);
> > -int xenbus_grant_ring(struct xenbus_device *dev, unsigned long ring_mfn);
> > -int xenbus_map_ring_valloc(struct xenbus_device *dev,
> > -                      int gnt_ref, void **vaddr);
> > -int xenbus_map_ring(struct xenbus_device *dev, int gnt_ref,
> > -                      grant_handle_t *handle, void *vaddr);
> > +int xenbus_grant_ring(struct xenbus_device *dev, void *vaddr,
> > +                 unsigned int nr_pages, grant_ref_t *grefs);
> > +int xenbus_map_ring_valloc(struct xenbus_device *dev, grant_ref_t 
> > *gnt_refs,
> > +                      unsigned int nr_grefs, void **vaddr);
> 
> In the definition nr_grefs is called grefs_order. From the usage I think
> the definition and not this prototype is correct.
> 

Good catch, thanks.

Wei.

> Ian.

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