Setting /proc/irq/<nr>/smp_affinity doesn't fail, but value doesn't change (when changing IRQ affinity manually)

Solution Verified - Updated -

Issue

When trying to change IRQ affinity manually, it doesn't work and doesn't give an error, for example:

# cat /proc/irq/51/smp_affinity
00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000040
# echo 10 > /proc/irq/51/smp_affinity
# cat /proc/irq/51/smp_affinity
00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000040
# echo "00000000,00000000,00000000,00000000,00000000,00000010" > /proc/irq/51/smp_affinity
# cat /proc/irq/51/smp_affinity
00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000040

Environment

  • Red Hat Enterprise Linux 5
  • 32/64-bit x86 architecture

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