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

Hi,

I'd like to revisit this now.

I'd like to commit this stuff as-is and then take some time to revisit
the catch-all softclock from cpu0 swi. It's more complicated than it
needs to be as it just assumes timeout_cpu == cpuid of cpu 0. So
there's no easy way to slide in a new catch-all softclock.

Once that's done I'd like to then experiment with turning on the pcpu
tcp timer stuff and gluing that into the RSS CPU ID / netisr ID stuff.

Thanks,

-a


On 20 February 2014 13:48, Adrian Chadd <adrian_at_freebsd.org> wrote:
> On 20 February 2014 11:17, John Baldwin <jhb_at_freebsd.org> wrote:
>
>> (A further variant of this would be to divorce cpu0's swi from the
>> catch-all softclock and let the catch-all softclock float, but bind
>> all the per-cpu swis)
>
> I like this idea. If something (eg per-CPU TCP timers, if it's turned
> on) makes a very specific decision about the CPU then it should be
> fixed. Otherwise a lot of the underlying assumptions for things like
> RSS just aren't guaranteed to hold.
>
> It could also perhaps extend to some abstract pool of CPUs later, if
> we wanted to do things like one flowing swi per socket or whatnot when
> we start booting on 1024 core boxes...
>
> -a