Re: [PATCH] cifs: remove the sockopt= mount option

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On Thu, Feb 21, 2013 at 10:27 AM, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> On Thu, 21 Feb 2013 10:00:07 -0600
> Steve French <smfrench@xxxxxxxxx> wrote:
>
>> We should do some quick performance runs to verify this - but with
>> corking and uncorking the socket explicitly presumably TCP_NODELAY
>> should not be needed.
>>
>
> I would think time for that sort of investigation was before you merged
> the patch that said we were going to remove it. I assumed that since
> you took that patch, you were OK with it.

Yes - I am ok with it and it didn't seem to hurt performance.
Corking/uncorking explicitly makes more sense if the complex network
layers work as expected - but the problem is that they change so best
to be safe and at least try some quick tests.

> In any case, I'll turn this question around...
>
> TCP_NODELAY says: Send frames as soon as possible after a sendmsg (or
> kernel_sendmsg in this case)
>
> TCP_CORK says: hold sending until I uncork the socket
>
> If the socket is CORK'ed then that overrides TCP_NODELAY (at least in
> my reading of the code). Since we always cork/uncork the socket now,
> what possible benefit could there be to keeping the sockopt=TCP_NODELAY
> option around?

None if corking/uncorking works as one would intuitively think - but
the tcp network layers under us are very complicated.

(I am not objecting to the patch to remove sockopt setting - just want
to do the simple checks to make sure we don't miss something)



-- 
Thanks,

Steve
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