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Subject: Re: [hwloc-devel] CPU affinity of OS Devices?
From: Samuel Thibault (samuel.thibault_at_[hidden])
Date: 2012-11-06 19:06:49


Guy Streeter, le Tue 06 Nov 2012 23:56:29 +0100, a écrit :
> My question is how do I specify a binding like "not on the same CPU
> that is handling the Ethernet interrupts"?

About interrupts, that's unfortunately actually not related with actual
topology of the machine, Linux is free to direct them to any processor,
which could be on another NUMA node at the other end of the machine.
There are even daemons to distribute them over time, meaning all CPUs
might handle the interrupt. I'm thus not sure we can even provide such
kind of information in a reliable way. You can for instance check in
/proc/irq/0/smp_affinity
that you probably have your timer interrupt potentially run by any
processor. You can modify the file in order to bind the interrupt to
some given CPU (which, again, can be very far from the actual PCI
device).

Samuel