On Tue, 19 Jan 2010, Clark Williams wrote: > RT-ers, > > Lately we've been struggling with some performance issues on high-core > count (>16 cores) NUMA machines with the RT kernel. During the course > of troubleshooting this issue, we tried using the 'numactl' program to > constrain our measurement testing tool (rteval) to a particular memory > node, rather than letting everything float. Doing so showed marked > improvement in both max latency and jitter. While this doesn't solve > our performance problems I thought it might make sense to have a --numa > mode for cylictest that compliments the --smp mode just added. > > The big difference here is that when using --numa, each measurement > thread (one per cpu) has it's stack allocated from the memory node > associated with it's cpu. Also, the major data structures for each > thread (parameter block, statistics block and histogram) are allocated > from the appropriate node. This is done with calls into libnuma, > which means this will add a dependency on libnuma. That might cause some trouble for embedded folks. :( > The intent is to measure latency on a numa system in the same way a > well-written RT application would run on a NUMA machine, that is > minimizing the off-node memory references. Agreed. tglx -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
