On Thu, Apr 16, 2009 at 07:52:25AM +0200, Otto Moerbeek wrote: > On Thu, Apr 16, 2009 at 07:47:14AM +0200, Henning Brauer wrote: > > > * Jason Dixon <ja...@dixongroup.net> [2009-04-16 07:18]: > > > We had a spare set of servers available, so I went back to the lab and > > > reproduced the traffic profile. I then tested the same load with the MP > > > kernel. My tests revealed that even though the kernel is not threaded, > > > we benefit from equal distribution of interrupts across all cores. Our > > > interrupt load effectively decreased by a factor of 4; since we aren't > > > performing any userland activity, the other 3 cores are otherwise > > > unused. > > > > was this 4.5 or earlier? If earlier what you saw could be pic vs apic. > > since 4.5 we have apic usually on UP too. > > if it isn't that, I am stunned. could speculate about better cache > > usage, but that would be about the only idea i'd have. It was a 2/28 snapshot, both cases (bsd vs bsd.mp).
> I think wrong statistics collection in the MP case should also be > considered as a possible cause. I've considered that as well. I was hoping someone smarter than me would have answers. :) -- Jason Dixon DixonGroup Consulting http://www.dixongroup.net/
