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Date: Tue, 18 Sep 2007 10:48:25 +0200 From: Ingo Molnar <mingo@...e.hu> To: Rob Hussey <robjhussey@...il.com> Cc: linux-kernel@...r.kernel.org, ck@....kolivas.org Subject: Re: Scheduler benchmarks - a follow-up * Rob Hussey <robjhussey@...il.com> wrote: > The obligatory graphs: > http://www.healthcarelinen.com/misc/benchmarks/BOUND_NOPREEMPT_lat_ctx_benchmark.png > http://www.healthcarelinen.com/misc/benchmarks/BOUND_NOPREEMPT_hackbench_benchmark.png > http://www.healthcarelinen.com/misc/benchmarks/BOUND_NOPREEMPT_pipe-test_benchmark.png btw., it's likely that if you turn off CONFIG_PREEMPT for .21 and for .22-ck1 they'll improve a bit too - so it's not fair to put the .23 !PREEMPT numbers on the graph as the PREEMPT numbers of the other kernels. (it shows the .23 scheduler being faster than it really is) > A cursory glance suggests that performance wrt lat_ctx and hackbench > has increased (lower numbers), but degraded quite a lot for pipe-test. > The numbers for pipe-test are extremely stable though, while the > numbers for hackbench are more erratic (which isn't saying much since > the original numbers gave nearly a straight line). I'm still willing > to try out any more ideas. the pipe-test behavior looks like an outlier. !PREEMPT only removes code (which makes the code faster), so this could be a cache layout artifact. (or perhaps we preempt at a different point which is disadvantageous to caching?) Pipe-test is equivalent to "lat_ctx -s 0 2" so if there was a genuine slowdown it would show up in the lat_ctx graph - but the graph shows a speedup. Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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