Messages in this thread | | | Date | Wed, 20 Jan 2010 07:51:41 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: RFC: NUMA modifications to cyclictest |
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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
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