On Fri, 2011-12-23 at 10:43 -0800, Suresh Siddha wrote: > On Wed, 2011-12-21 at 18:16 -0800, Shi, Alex wrote: > > On Thu, 2011-12-22 at 10:03 +0800, Siddha, Suresh B wrote: > > > On Wed, 2011-12-21 at 17:31 -0800, Shi, Alex wrote: > > > > This patch partly fixed a performance regression that triggered by > > > > 4dcfe1025b513c2c, but issue still exists. > > > > > > So how much was the regression caused by the commit 4dcfe1025b513c2c and > > > how much did we recover with this fix I posted. If we are talking about > > > the regression caused by this single commit 4dcfe1025b513c2c, then I > > > don't know of any other related fixes other than the recent fix we > > > pushed upstream (ab2789213d224202237292d78aaa0c386c7b28b2). > > > > A little complex for the whole thing. > > on 4 sockets EX machine, 3~5% hackbench thread regression due to 4dcfe > > can be recovered by ab2789. > > > > But on 2 sockets SNB machine, 1024 clients loop netperf TCP-RR has about > > 9% regression. and your patch seem recover 2~3%. > > > > And on a 2 sockets nhm, one of our private benchmark was impact much 20 > > +% regression. that benchmark just run 4 process, each of process open a > > thread, and the thread tasks is to locate randomly pages and than read > > from 4 times/write 1 time data into a page. The ab2789 commit seems no > > help our benchmark. > > Ok. Can you please try couple of experiments with two kernels? Two > kernels being the base kernel (prior to 4dcfe1025b513c2c) and the second > kernel with the commit ab2789213d224202237292d78aaa0c386c7b28b2. > > One experiment with p-states turned off and the second experiment with > c-states turned off. I did testing on both of kernel with setting 'performance' gov for all CPU P-states, and disable cpuidle by setting cpuidle.off=1 in cmdline. But didn't find measurable impact on performance result. > > I suspect mostly deeper core c-states might be contributing to the > behavior that you are seeing. > > thanks, > suresh > -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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