[nkurz]

Oh and also don't forget to set up IRQ affinity to avoid any of those cores to handle.

Perhaps this is what you meant, but this is straightforward. Simply disabling 'irqbalance' is a simple way to do this. Alternatively, you can also configure it to cooperate with 'isolcpus' by using 'FOLLOW_ISOLCPUS'.

[rdtsc]

Disabling it will disable auto-balancing it, it will just become static, which might not be the exact configuration you want.

[nkurz]

Yes, if you don't want all interrupts to handled by CPU0 you'll need a different approach. But doing anything else may be more difficult than it sounds. Do you know if the bug mentioned here is fixed?

http://serverfault.com/questions/380935/how-to-ban-hardware-...

http://code.google.com/p/irqbalance is 403 for me and I haven't been able to check.

[rdtsc]

Setting IRQ affinity for network controllers to either follow or not follow the "high priority" processes seems to do the trick.

I usually do stuff described here:

https://cs.uwaterloo.ca/~brecht/servers/apic/SMP-affinity.tx...

And sometimes following ends up better (same cache), sometimes isolating ends up being better.