I have 12 core boxes:

egrep -c processor /proc/cpuinfo

cat /proc/irq/default_smp_affinity

I would like to use all of the cores so my understanding is that the default_smp_affinity should be set to ffffffffffff.

echo ffffffffffff > /proc/irq/default_smp_affinity
-bash: echo: write error: Value too large for defined data type

How can I make sure that all of the cores are equally used and the default_smp_affinity is set correctly?


cat /etc/issue.net
CentOS release 6.5 (Final)


2.6.32-431.23.3.el6.x86_64 #1 SMP Thu Jul 31 17:20:51 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

Any input is appreciated.

  • Can you give some more context on what you're trying to do? – ewwhite Sep 25 '14 at 19:07
  • 1
    Is the irqbalance daemon running? – ewwhite Sep 25 '14 at 19:32
  • I think 'fff' is ok, because each bit is for one cpu, so this 'fff' has 12bits set. What makes you believe all cpus are not used? Is there some output of top or sar or other tool ? – tonioc Sep 25 '14 at 21:15

Actually the fff is the right setting for a 12 core box. The IRQ distribution was not sooth enough this is why I thought it might be misconfigured.

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