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Date: Tue, 20 Jan 2015 08:58:34 +0100
From: Hans Petter Selasky <hps@selasky.org>
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To: Konstantin Belousov <kostikbel@gmail.com>
Subject: Re: svn commit: r277213 - in head: share/man/man9 sys/kern
 sys/ofed/include/linux sys/sys
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Cc: "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>,
 Adrian Chadd <adrian@freebsd.org>,
 "src-committers@freebsd.org" <src-committers@freebsd.org>,
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On 01/20/15 08:51, Konstantin Belousov wrote:
> On Tue, Jan 20, 2015 at 05:30:25AM +0100, Hans Petter Selasky wrote:
>> On 01/19/15 22:59, Adrian Chadd wrote:
>>> Hi,
>>>
>>> Would you please check what the results of this are with CPU specific
>>> callwheels?
>>>
>>> I'm doing some 10+ gig traffic testing on -HEAD with RSS enabled (on
>>> ixgbe) and with this setup, the per-CPU TCP callwheel stuff is
>>> enabled. But all the callwheels are now back on clock(0) and so is the
>>> lock contention. :(
>>>
>>> Thanks,
>>>
>>
>> Hi,
>>
>> Like stated in the manual page, callout_reset_curcpu/on() does not work
>> with MPSAFE callouts any more!
> I.e. you 'fixed' some undeterminate bugs in callout migration by not
> doing migration at all anymore.
>
>>
>> You need to use callout_init_{mtx,rm,rw} and remove the custom locking
>> inside the callback in the TCP stack to get it working like before!
>
> No, you need to do this, if you think that whole callout KPI must be
> rototiled.  It is up to the person who modifies the KPI, to ensure that
> existing code is not broken.
>
> As I understand, currently we are back to the one-cpu callouts.
> Do other people consider this situation acceptable ?
>

Hi Konstantin,

Please read the callout 9 manual page first.

--HPS