Messages in this thread |  | | Date | Sun, 15 Jul 2001 17:58:56 -0700 | From | Mike Kravetz <> | Subject | Re: [Lse-tech] Re: CPU affinity & IPI latency |
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On Sun, Jul 15, 2001 at 12:00:38PM -0500, Troy Benjegerdes wrote: > > The next very interesting thing I found was that if I run something like > 'while true; do true; done' to load the other CPU while gzip is running, > gzip runs faster. The time change isn't very large, and appears to be just > barely detectable above the noise, but it definetly appears that gzip is > bouncing back and forth between cpus if both are idle. > > I'm tempted to try the somewhat brute-force approach of increasing > PROC_CHANGE_PENALTY, which is currently set to 20 (on ppc) to something > like 100. Would this be an adequate 'short-term' solution util there is > some sort of multi-queue scheduler that everyone Linus likes? What are the > drawbacks of increasing PROC_CHANGE_PENALTY?
I'm pretty sure changing the value of PROC_CHANGE_PENALTY will not help in this case. PROC_CHANGE_PENALTY becomes increasingly important as the number of running tasks is increased. In the case of simply running one task (like gzip) on your 2 CPU system, I don't think it will make any difference.
-- Mike Kravetz mkravetz@sequent.com IBM Linux Technology Center - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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