linux-kernel - Re: [PATCH][RFC] x86: Fix the irq affinity in fixup

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Date:   Wed, 5 Jul 2017 08:46:08 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Chen Yu <yu.c.chen@...el.com>
cc:     Ingo Molnar <mingo@...hat.com>, "H. Peter Anvin" <hpa@...or.com>,
        Borislav Petkov <bp@...e.de>, Len Brown <len.brown@...el.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>, x86@...nel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH][RFC] x86: Fix the irq affinity in fixup_cpus

On Wed, 5 Jul 2017, Chen Yu wrote:
> On Tue, Jul 04, 2017 at 10:50:33AM +0200, Thomas Gleixner wrote:
> Here's the test result for affinity:
> # uname -r
> 4.12.0+
> # cat /proc/irq/32/smp_affinity
> 00000000,80000000
> # echo 0 > /sys/devices/system/cpu/cpu31/online 
> # cat /proc/irq/32/smp_affinity
> 00000000,ffffffff
> Looks like cpu31 is till included in the irq mask.

Yes, because the offline broke affinity and now it's reset to the default
affinity mask. /proc/irq/*/affinity is the affinity which is allowed by the
admin, not the one which is effective.

Look at /proc/irq/32/effective_affinity to see where it's really routed to.

Thanks,

	tglx