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Date: Tue, 25 Mar 2008 21:29:34 +0100 From: "J.C. Pizarro" <jcpiza@...il.com> To: LKML <linux-kernel@...r.kernel.org> Subject: Poor performance now? Please, put weighted velocities ctxts/s to the sched.decision! [1] "Performance changes between 2.6.13 and 2.6.23" http://lkml.org/lkml/2008/3/25/102 On Tue, Mar 25, 2008 at 1:34 PM, Sanders, Rob M. <sanders-rob@....com> wrote: > Of more particular concern, the main application that I build has seen a 4-5X > slowdown in performance. Under YDL4.0.91 I could process roughly 1e8 data > points in ~2 seconds, and under YDL6.0 I now process 1e8 data points in > ~8 seconds. Total CPU loading (from top) is about 5%, under both systems. ... > YDL4.0.91 system is context switching about 7000 per interval, whereas the > YDl6 system is context switching about 1200 times per interval. It's the velocity, ctxts/interval, a parameter not recognized by the scheduler. I said them to put the proposal of putting the counters and velocities fields to the task's struct for the scheduler can take a good decision, the past month. More weight in higher ctxts/s for the scheduler=> more interactivity. [2] "Re: Serious performance regression in Wine applications and Linux 2.6.24.*" http://lkml.org/lkml/2008/3/25/181 On Tue, 25 Mar 2008 08:49:13 -0700, "Ray Lee" wrote: > Andi's idea of looking for excessive context switches is good -- I > didn't see a response to that one. Other than that, if you're only > noticing the issue in 3d games, then it could be several things (not > just the scheduler). The kernel needed the velocity parameter to gain it: ctxts per interval (normally ctxts/s or ctxts/minute). The proposal of the past month was here: "Please, put 64-bit counter per task and incr.by.one each ctxt switch." http://lkml.org/lkml/2008/2/23/398 http://lkml.org/lkml/2008/2/23/401 http://lkml.org/lkml/2008/2/23/406 http://lkml.org/lkml/2008/2/24/1 http://lkml.org/lkml/2008/2/24/103 http://lkml.org/lkml/2008/2/24/157 http://lkml.org/lkml/2008/2/26/159 My proposal is free for yours, quasi-bastards, I won't charge you! J.C.Pizarro -- 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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