Re: [rfc] bind per-cpu timeout threads to each CPU

On 19 February 2014 11:40, Alexander Motin <mav_at_freebsd.org> wrote:
> Hi.
>
> Clock interrupt threads, same as other ones are only softly bound to
> specific CPUs by scheduler preferring to run them on CPUs where they are
> scheduled. So far that was enough to balance load, but allowed threads to
> migrate, if needed. Is it too flexible for some use case?

I saw it migrate under enough CPU load / pressure, right smack bang in
the middle of doing TCP processing.

So if we're moving towards supporting (among others) a pcbgroup / RSS
hash style work load distribution across CPUs to minimise
per-connection lock contention, we really don't want the scheduler to
decide it can schedule things on other CPUs under enough pressure.
That'll just make things worse.


-a