Re: [Problem] about src/xen/include/public/io/ring.h

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Fri, Apr 12, 2013 at 07:24:52PM +0800, 马磊 wrote:
> >
> > This stuff is quite difficult to describe in words. Perhaps you would
> > find it helpful to draw the ring and the 4 pointers and to consider what
> > happens when each pointer catches up to (but doesn't pass) the one in
> > front, and what this tells you about the number of requests/responses
> > which are on the ring at that time.
> >
> >
> Could you show me a rough figure for describing unconsumed requests in a
> specific scene.

It would be easier if you just instrumented the code in question to see
how it works.
> 
> 
> > Then remember that the ring is actually represented as a single page of
> > memory, with the pointers logically wrapping from +4096 (==PAGE_SIZE)
> > back to +0.
> >
> > Ian.
> >
> >
> You mean the ring is a circle buffer except for the ring header.

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