SMP affinity MSI-X interrupts

From: Anil Ravindranath
Date: Wed Sep 22 2010 - 14:29:33 EST


Hi,

I have a Dual Core(and also Quad core) system and a controller which has
MSI-X interrupts.

What I noticied is that all interrupts coming only on CPU0. The
system/config is SMP aware.

As we undestand, I try to modify /proc/irq/num/smp_affinity settings to
get the interrupts for more than one core, what I noticied is if I change
it to lets say "2", I start getting interrupts only on CPU1. Now I change it
to "3", but I don't getting interrupts on CPU0 and CPU1. Its not taking
more than one CPU mask value.

I checked the irq_set_affinity() function and found that it need couple
of config settings like CONFIG_SMP and CONFIG_GENERIC_PENDING_IRQ and both
are set in my config.

Looks like, the function irq_affinity_write_proc( ) is also taking "3"
(more than one CPU mask) correctly.

The irqbalancer is ON . Is there anyother CONFIG setting I am
missing?

I am using a Distro kernel very latest (2.6.32 based). I can try on a
latest kernel as well.

with regards,
Anil
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