Messages in this thread | | | Date | Tue, 28 Aug 2007 21:19:25 +0200 | From | Willy Tarreau <> | Subject | Re: CFS review |
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On Tue, Aug 28, 2007 at 10:02:18AM +0200, Ingo Molnar wrote: > > * Xavier Bestel <xavier.bestel@free.fr> wrote: > > > Are you sure they are stalled ? What you may have is simple gears > > running at a multiple of your screen refresh rate, so they only appear > > stalled. > > > > Plus, as said Linus, you're not really testing the kernel scheduler. > > gears is really bad benchmark, it should die. > > i like glxgears as long as it runs on _real_ 3D hardware, because there > it has minimal interaction with X and so it's an excellent visual test > about consistency of scheduling. You can immediately see (literally) > scheduling hickups down to a millisecond range (!). In this sense, if > done and interpreted carefully, glxgears gives more feedback than many > audio tests. (audio latency problems are audible, but on most sound hw > it takes quite a bit of latency to produce an xrun.) So basically > glxgears is the "early warning system" that tells us about the potential > for xruns earlier than an xrun would happen for real. > > [ of course you can also run all the other tools to get numeric results, > but glxgears is nice in that it gives immediate visual feedback. ]
Al could also test ocbench, which brings visual feedback without harnessing the X server : http://linux.1wt.eu/sched/
I packaged it exactly for this problem and it has already helped. It uses X after each loop, so if you run it with large run time, X is nearly not sollicitated.
Willy
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