Messages in this thread | | | Date | Fri, 20 Aug 1999 16:53:49 -0400 (EDT) | From | Jonathan Case Nicklin <> | Subject | Re: [patch] SMP scheduler improvements |
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Andr`ea,
There was a small typo in the reference 2.2.11 results:
incorrect 128: 4387 correct 128: 4417
sorry abou that, JCN
.`'. .`'. .`'. `.,' `.,' `.,' frizzle@engin.umich.edu "The facts, no matter how interesting they may .`'. .`'. .`'. be, are irrelevant!" `.,' `.,' `.,' (A thought to get you through any crisis)
On Fri, 20 Aug 1999, Jonathan Case Nicklin wrote:
> Andr`ea, > I benchmarked a patched version of 2.2.11 vs. the reference, and found > some areas of concern: a slight performance degradation and a potential > impact on real-time performance. I'm hoping you can clarify these for > me. > > Using the SDM1.1 057.SDET benchmark I obtained the following. > > Reference 2.2.11: > scripts throughput > 32 6133 > 64 5599 > 96 4978 > 128 4387 > 150 4044 > > Patched 2.2.11: > scripts throughput > 32 6106 > 64 5515 > 96 4928 > 128 4387 > 150 4022 > > *these results were averaged over 20 runs and run under identical > system states. > > Using make I obtained the following: > Reference 2.2.11: > Real: 77.82 > User: 198.26 > Sys: 20.52 > > Patched 2.2.11: > Real: 77.94 > User: 199.44 > Sys: 18.70 > > As you can see, I found a (slight) performance decrease according to > the benchmark. > > I agree with your conceptual view of the situation, so this is a little > bit of a surprise. Are these the same benchmark results you came up > with, or did I mismeasure somehow? > > Also, it looks to me like you removed some code in reschedule_idle > necessary for good real-time performace, in particular, evaluating the > preemptive_goodness of a task vs all of the tasks on all other CPU's. > From where I sit, it looks like your implementation evaluates the > preemptive goodness on the best_cpu only after checking avg_timeslice > vs. cache flush time. The potential impact of this on real-time > performance might be pretty drastic -- what do you think? > > Maybe it would be worthwhile to evaluate avg_timeslice vs cacheflush > time in goodness? > > -JCN > > - > Linux SMP list: FIRST see FAQ at http://www.irisa.fr/prive/mentre/smp-faq/ > To Unsubscribe: send "unsubscribe linux-smp" to majordomo@vger.rutgers.edu >
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