linux-kernel - Re: irq/0/smp_affinity =3 doesn't seem to work

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Message-Id: <1165346347.3233.396.camel@laptopd505.fenrus.org>
Date:	Tue, 05 Dec 2006 20:19:07 +0100
From:	Arjan van de Ven <arjan@...radead.org>
To:	"Raz Ben-Jehuda(caro)" <raziebe@...il.com>
Cc:	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: irq/0/smp_affinity =3 doesn't seem to work

On Tue, 2006-12-05 at 21:14 +0200, Raz Ben-Jehuda(caro) wrote:
> On 12/5/06, Arjan van de Ven <arjan@...radead.org> wrote:
> > On Tue, 2006-12-05 at 18:30 +0200, Raz Ben-Jehuda(caro) wrote:
> > > hello.
> > >
> > > I have a dual cpu AMD machine, I noticed that
> > > only one timer0 is working in /proc/interrutps.
> > > setting proc/irq/0/smp_affinity to 3 does make
> > > any difference.
> >
> > if you set it to 3 then the chipset gets to decide where the irq goes.
> > Many decide to send it to the first cpu.
> >
> > (not that it matters, the timer is so low frequency that it can go
> > anywhere without problems)
> >
> > --
> > if you want to mail me at work (you don't), use arjan (at) linux.intel.com
> > Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org
> >
> >
> thanks Arjan.
> 
> Yet something is not clear to me.
> To the best of my knowledge , each cpu run its own schedule routine.
> So, if only cpu0 gets timer0 interrupts, how does cpu1
> gets to run the schedule function 
> what interrupts cpu1' current task  ?

the scheduler code uses IPI's for that...


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