Re: [PATCH V2] x86/irq: Cure live lock in fixup_irqs()

From: Luck, Tony
Date: Thu Mar 17 2016 - 17:16:13 EST


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@xxxxxxxxx>

-Tony