2012-10-09 16:39:23

by Roger Pau Monne

[permalink] [raw]
Subject: Re: [Xen-devel] [PATCH v2] Persistent grant maps for xen blk drivers

On 24/09/12 13:36, Jan Beulich wrote:
>>>> On 21.09.12 at 17:52, Oliver Chick <[email protected]> wrote:
>> Changes since v1:
>>
>> * Maximum number of persistent grants per device now 64, rather than
>> 256, as this is the actual maxmimum request in a (1 page) ring.
>
> As said previously, I don't see why this needs to have a separate
> #define at all - it's simply __RING_SIZE(). No adding this would
> also imply that - apart from perhaps documenting the new xenstore
> nodes - io/blkif.h would need changing at all (which otherwise would
> require a hypervisor side patch to be submitted too).

I've been working on this a little bit more, and __RING_SIZE returns 32
for all ring types (blkif, blkif_x86_32 and blkif_x86_64), any specific
reason to choose __RING_SIZE()*2?