I'll occasionally get errors in /var/log/messages indicating that irqbalance has tried to peg an interrupt to offline CPUs in SMT=1 or SMT=2 modes.
According to irqbalance documentation, I should set the IRQBALANCE_BANNED_CPUS bitmask to avoid this problem.
For a four-socket, eight core P7 system, my mask would look like 32 hexadecimal "e" characters, which on RHEL 5 can be set in /etc/sysconfig/irqbalance
I just wanted to run this by the forum to see if my logic made sense, and whether anybody else has run into this, tried this fix, or has contrary experience.
SystemAdmin 110000D4XK706 Posts
Re: Avoiding SMT issues with IRQ balance2010-05-25T20:26:54ZThis is the accepted answer. This is the accepted answer.Checking. Just to be sure, is the system completely in SMT=1 or SMT=2 mode? in other words, ppc64_cpu reports the correct mode for the whole system?
# ppc64_cpu --smt smt=2
Second, is this causing any unexpected behavior?
nfont 270000FBVC1 Post
Re: Avoiding SMT issues with IRQ balance2010-05-27T19:58:32ZThis is the accepted answer. This is the accepted answer.
- chwilk 270002HB28
I think something that would catch all changes to smt state may be a better solution, but am not sure how easy that would be.