Re: PROBLEM: Timer interrupt lockup on HT machine

[Mikael Pettersson]

Martin Wilck writes:
 > Another observation is that on the HT machines (whether or not the
 > above problem occurs) almost all interrupts seem to be handled by CPU 0.
 > 
 > CPU 1 gets a few, but in a ratio of about 1:10000 wrt CPU 0.
 > CPU 2 and 3 do not see any interrupts at all.
 > 
 > Has anybody heard of these problems yet, and are workarounds available?

I've heard about that IRQ imbalance on MP P4 Xeons from a person at Dell.
My understanding of it is that it's a consequence of the local APIC
priorization changes Intel did in the P4 xAPIC design. (Study Intel's IA32
Vol 3 manual in detail and you'll see them.) Supposedly Ingo Molnar is
working on a solution.

/Mikael