Re: [PATCH 2/2] drivers: xen/block: add multi-page ring support

[Bob Liu <bob.liu@oracle.com>]

On 02/06/2015 07:01 PM, Wei Liu wrote:
> On Fri, Feb 06, 2015 at 06:47:17PM +0800, Bob Liu wrote:
>>
>> On 02/02/2015 06:43 PM, Roger Pau Monné wrote:
>>> El 23/01/15 a les 10.14, Bob Liu ha escrit:
>>>> Extend xen/block to support multi-page ring.
>>>>  * xen-blkback notify blkfront with feature-multi-ring-pages
>>>>  * xen-blkfront write to xenstore about how many pages are used as the ring
>>>>
>>>> If using 4 pages as the ring, inflight requests inscreased from 32 to 128 and
>>>> IOPS improved nearly 400% on our system.
>>>>
>>>> Signed-off-by: Bob Liu <bob.liu@oracle.com>
>>>> ---
>>>>  drivers/block/xen-blkback/xenbus.c |   86 +++++++++++++++++++++++++--------
>>>>  drivers/block/xen-blkfront.c       |   94 ++++++++++++++++++++++++++----------
>>>
>>> This requires a patch to xen/include/public/io/blkif.h in the Xen
>>> repository describing how this protocol extension is going to work
>>> before reviewing the Linux implementation.
>>>
>>
>> But there is no protocol change, just add an parameter "max_ring_pages"
>> to control how many pages can be used as the ring. Now with one page we
>> can only have 32 requests.
>>
> 
> I think Roger meant the xenbus protocol used to negotiate this feature,
> not the data protocol regarding how request and response are
> interpreted. Blkif.h (and netif.h FWIW) has section to describe xenbus
> protocol.
> 

Oh, I see. Sorry for the misunderstood.
Also will fix the indentation issue of the first patch.

Thanks,
-Bob