TCP stack lock contention with short-lived connections

[k simon]

Hi,

   Does any plan commit and MFC to the 10-stable ?


Regards
Simon

于 14-5-29 0:42, Julien Charbon 写道:
>
>   Hi,
>
> On 23/05/14 22:52, Julien Charbon wrote:
>> On 23/05/14 14:06, Julien Charbon wrote:
>>> On 27/02/14 11:32, Julien Charbon wrote:
>>>> On 07/11/13 14:55, Julien Charbon wrote:
>>>>> On Mon, 04 Nov 2013 22:21:04 +0100, Julien Charbon
>>>>> <jcharbon at verisign.com> wrote:
>>>>>> I have put technical and how-to-repeat details in below PR:
>>>>>>
>>>>>> kern/183659: TCP stack lock contention with short-lived connections
>>>>>> http://www.freebsd.org/cgi/query-pr.cgi?pr=183659
>>>>>>
>>>>>>   We are currently working on this performance improvement
>>>>>> effort;  it
>>>>>> will impact only the TCP locking strategy not the TCP stack logic
>>>>>> itself.  We will share on freebsd-net the patches we made for
>>>>>> reviewing and improvement propositions;  anyway this change might
>>>>>> also
>>>>>> require enough eyeballs to avoid tricky race conditions introduction
>>>>>> in TCP stack.
>>
>>   Joined the two cumulative patches (tcp-scale-inp-list-v1.patch and
>> tcp-scale-pcbinfo-rlock-v1.patch) we discussed the most at BSDCan 2014.
>
>   At BSDCan 2014 we were also asked to provide flame graph [1][2] to
> highlight impacts of these TCP changes.  The Dtrace sampling was done on
> a NIC receive queue IRQ bound core.
>
>   o First CPU flame graph on 10.0-RELENG at 40k TCP connection/secs:
>
> https://googledrive.com/host/0BwwgoN552srvQi1JWG42TklfQ28/releng10-40k.html
>
>   Note:
>
>   - __rw_wlock_hard on ipi_lock contention is clear as usual.
>
>   o Second, same test with all our patches applied (thus from 10.0-next
> branch [3]):
>
> https://googledrive.com/host/0BwwgoN552srvQi1JWG42TklfQ28/tcp-scale-40k.html
>
>
>    Note:
>
>   - Almost all __rw_wlock_hard on ipi_lock contention is converted in
> idle time.
>
>   o Third, still using 10.0-next branch, the flame graph when doubling
> the rate to 80k TCP connection/sec:
>
> https://googledrive.com/host/0BwwgoN552srvQi1JWG42TklfQ28/tcp-scale-80k.html
>
>
>   My 2 cents.
>
> [1] http://www.brendangregg.com/FlameGraphs/cpuflamegraphs.html
> [2] https://wiki.freebsd.org/201405DevSummit/NetworkStack
> [3] https://github.com/verisign/freebsd/commits/share/10.0-next
>
> --
> Julien
>
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