svn commit: r265792 - head/sys/kern

[Slawa Olhovchenkov]

On Sat, May 10, 2014 at 12:53:37AM +0000, Adrian Chadd wrote:

> Author: adrian
> Date: Sat May 10 00:53:36 2014
> New Revision: 265792
> URL: http://svnweb.freebsd.org/changeset/base/265792
> 
> Log:
>   Add in support to optionally pin the swi threads.
>   
>   Under enough load, the swi's can actually be preempted and migrated
>   to other currently free cores.  When doing RSS experiments, this lead
>   to the per-CPU TCP timers not lining up any more with the RX CPU said
>   flows were ending up on, leading to increased lock contention.
>   
>   Since there was a little pushback on flipping them on by default,
>   I've left the default at "don't pin."
>   
>   The other less obvious problem here is that the default swi
>   is also the same as the destination swi for CPU #0.  So if one
>   pins the swi on CPU #0, there's no default floating swi.
>   
>   A nice future project would be to create a separate swi for
>   the "default" floating swi, as well as per-CPU swis that are
>   (optionally) pinned.

MFC planed?
I have 10.0 box with aprox. 16Gbit TCP at peak.