Re: [PATCH v5] xenbus_client: extend interface to suppurt multi-page ring

[David Vrabel <david.vrabel@citrix.com>]

On 19/11/13 17:14, Wei Liu wrote:
> On Tue, Nov 19, 2013 at 05:09:29PM +0000, David Vrabel wrote:
>> On 10/11/13 17:21, 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.
>>>
>>> Affected Xen drivers:
>>> * blkfront/back
>>> * netfront/back
>>> * pcifront/back
>>> * tpmfront
>>>
>>> The interface is documented, as before, in xenbus_client.c.
>>
>> It looks ok to me so I guess:
>>
>> Reviewed-by: David Vrabel <david.vrabel@citrix.com>
>>
>> But, I think this should wait until either:
>>
>> a) There's an in kernel user that uses multipage rings
>>
> 
> The main point I picked this up is there seems to be people interested
> in this during Xen developer summit. None of the users is in tree
> though.
> 
>> or
>>
>> b) You demonstrate multi page rings have been tested with some sort of
>> unit test.
>>
> 
> Wait until I have time to develop multi page ring for network driver?

I said unit test.  A test driver that creates a multipage ring, maps it
and verifies that reads/writes to the two different mappings (i.e,
'front' and 'back') work as expected.  This shouldn't be a lot of work.

We can't take a new feature that hasn't been tested at all.

David