Re: [PATCH v1 05/18] xprtrdma: Avoid using Write list for small NFS READ requests

Chuck Lever
2016-04-11T20:38:44Z

> On Apr 11, 2016, at 4:35 PM, Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org> wrote:
>
>> Avoid the latency and interrupt overhead of registering a Write
>> chunk when handling NFS READ requests of a few hundred bytes or
>> less.
>>
>> This change does not interoperate with Linux NFS/RDMA servers
>> that do not have commit 9d11b51ce7c1 ('svcrdma: Fix send_reply()
>> scatter/gather set-up').
>>
>> $ git describe 9d11b51ce7c1
>> v4.2-rc3-10-g9d11b51
>>
>
> Hey Chuck,
>
> Is there any way to avoid breaking interoperability with older servers?

No, pre-4.2 Linux servers have a bug that can be fixed by
applying the above commit, which shouldn't be difficult to
backport.

Clients have always been allowed to send NFS READ this way.

--
Chuck Lever

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