Date: Wed, 02 May 2012 14:39:41 -0700 From: Navdeep Parhar <np@FreeBSD.org> To: Ryan Stone <rysto32@gmail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: CPU selection for ithreads on 8.3 Message-ID: <4FA1A99D.208@FreeBSD.org> In-Reply-To: <CAFMmRNzHTqOasjq20e61o90PkZQ0vRWF9B-DWk=Qw3vO3CKdhg@mail.gmail.com> References: <4FA1A421.6020601@FreeBSD.org> <CAFMmRNzHTqOasjq20e61o90PkZQ0vRWF9B-DWk=Qw3vO3CKdhg@mail.gmail.com>
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On 05/02/12 14:28, Ryan Stone wrote:
> On Wed, May 2, 2012 at 5:16 PM, Navdeep Parhar<np@freebsd.org> wrote:
>> There seems to be a regression in 8.3 in the way the kernel selects CPUs
>> for interrupts. For example, cxgb(4) on 8.3 ends up with all
>> its ithreads on the same CPU (CPU7 in this case).
>>
>> 12 root -68 - 0K 816K WAIT 7 0:55 0.00% intr{irq279:
>> cxgbc0}
>> 12 root -68 - 0K 816K WAIT 7 0:52 0.00% intr{irq275:
>> cxgbc0}
>> 12 root -68 - 0K 816K WAIT 7 0:47 0.00% intr{irq278:
>> cxgbc0}
>> 12 root -68 - 0K 816K WAIT 7 0:43 0.00% intr{irq277:
>> cxgbc0}
>> 12 root -68 - 0K 816K WAIT 7 0:43 0.00% intr{irq282:
>> cxgbc0}
>> 12 root -68 - 0K 816K WAIT 7 0:41 0.00% intr{irq281:
>> cxgbc0}
>> 12 root -68 - 0K 816K WAIT 7 0:32 0.00% intr{irq276:
>> cxgbc0}
>> 12 root -68 - 0K 816K WAIT 7 0:31 0.00% intr{irq280:
>> cxgbc0}
>>
>> Back in the day there used to be code in cxgb to bind different
>> interrupts to different CPUs but it was removed because the kernel
>> distributed them across CPUs anyway. So what changed? This appears 8.3
>> specific. I don't see it on head and I don't have a 9 system readily
>> available right now.
>
> Does r232757 fix this? That just missed 8.3-RELEASE.
I will try it. But would this explain why it used to work with 8.2 but
broke in 8.3?
Navdeep
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