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Date:      Fri, 9 May 2014 12:33:58 -0700
From:      Adrian Chadd <adrian@freebsd.org>
To:        John Baldwin <jhb@freebsd.org>
Cc:        Alexander Motin <mav@freebsd.org>, freebsd-current <freebsd-current@freebsd.org>, "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org>
Subject:   Re: [rfc] bind per-cpu timeout threads to each CPU
Message-ID:  <CAJ-VmokL40MGY2=sKAtvgMBKHt6ZRY9ZfnZ1Mj5y1qAa4ANC=A@mail.gmail.com>
In-Reply-To: <201405091349.14381.jhb@freebsd.org>
References:  <530508B7.7060102@FreeBSD.org> <CAJ-VmonUiSeCxnbYcjtWZ8uxa0c2ys5Za_GMLQenwu8zmEuFpQ@mail.gmail.com> <CAJ-VmonmrB7Z-PKH7P1DOJjSvFD_nRHqaiFJUuwvHoTUtiEVoQ@mail.gmail.com> <201405091349.14381.jhb@freebsd.org>

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On 9 May 2014 10:49, John Baldwin <jhb@freebsd.org> wrote:
> On Thursday, May 08, 2014 11:43:39 pm Adrian Chadd wrote:
>> 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,
>
> To be clear, are you going to commit the change to bind all but CPU 0
> to their CPU but let the "default" swi float for now?  I think that is
> fine to commit, but I wouldn't want to bind the "default" swi for now.

I'd like to do it in the other order and bind everything, so things
like the per-CPU TCP timer thing can be flipped on for RSS and
actually be useful.

I'm looking into what it'd take to create a separate default swi as
well as a cpu-0 swi but as I said, it's pretty hairy there.

How about i instead do the comprimise:

* i'll pin all other swi's
* default swi isn't pinned by default, but one can flip on a sysctl at
boot time to pin it

How's that sound?


-a



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