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Date: Wed, 5 Jul 2017 08:46:08 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: Chen Yu <yu.c.chen@intel.com>
cc: Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
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        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH][RFC] x86: Fix the irq affinity in fixup_cpus
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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