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Date: Thu, 17 Mar 2016 14:14:40 -0700
From: "Luck, Tony" <tony.luck@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>, Harry Junior <harryjr@outlook.fr>,
        x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
        Joe Lawrence <joe.lawrence@stratus.com>,
        Borislav Petkov <bp@alien8.de>, Ben Hutchings <ben@decadent.org.uk>
Subject: Re: [PATCH V2] x86/irq: Cure live lock in fixup_irqs()
Message-ID: <20160317211439.GA21968@intel.com>
References: <alpine.DEB.2.11.1603140931430.3657@nanos>
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This version also passes repeated iterations of:

# echo 0 | tee /sys/devices/system/cpu/cpu*/online
# echo 1 | tee /sys/devices/system/cpu/cpu*/online


Some of the time taken in the offline cycle may be
a more than O(N) chasing of IRQs onto an ever smaller
available set of online cpus.  There are over 4000
lines like this:

[  218.220045] Broke affinity for irq 66

on the console for each offline pass.

Also a couple of these:

[  221.951171] IRQ fixup: irq 68 move in progress, old vector 79

for each pass offlining all but one cpu.


Tested-by: Tony Luck <tony.luck@intel.com>

-Tony