On Tue, Oct 16, 2007 at 12:07:06PM -0700, Ken Chen wrote: > We recently discovered a nasty performance bug in the kernel CPU load > balancer where we were hit by 50% performance regression. > > When tasks are assigned to a subset of CPUs that span across > sched_domains (either ccNUMA node or the new multi-core domain) via > cpu affinity, kernel fails to perform proper load balance at > these domains, due to several logic in find_busiest_group() miss > identified busiest sched group within a given domain. This leads to > inadequate load balance and causes 50% performance hit. > > To give you a concrete example, on a dual-core, 2 socket numa system, > there are 4 logical cpu, organized as:
oops, this issue can easily happen when cores are not sharing caches. I think this is what happening on your setup, right? thanks, suresh - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/