Messages in this thread | | | Subject | Re: scheduler nice 19 versus 'idle' behavior / static low-priority scheduling | From | Nathanael Hoyle <> | Date | Fri, 30 Jan 2009 05:18:20 -0500 |
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On Fri, 2009-01-30 at 10:03 +0100, Peter Zijlstra wrote: > On Fri, 2009-01-30 at 04:00 -0500, Nathanael Hoyle wrote: > > On Fri, 2009-01-30 at 09:50 +0100, Peter Zijlstra wrote: > > > On Fri, 2009-01-30 at 00:49 -0500, Nathanael Hoyle wrote: > > > > > > > > 1) Is my problem 'expected' based on others' understanding of the > > > > current design of the scheduler, or do I have a one-off problem to > > > > troubleshoot here? > > > > > > What kernel are you running (or did my eye glance over that detail in > > > your longish email) ? > > > > > > > I didn't include it, I should have: > > > > $ uname -a > > Linux nightmare 2.6.27-gentoo-r7-nhoyle #2 SMP Wed Jan 28 19:04:37 EST > > 2009 x86_64 Intel(R) Core(TM)2 Quad CPU Q9450 @ 2.66GHz GenuineIntel > > GNU/Linux > > Ah, then please do as Mike suggested, try 28.2 or 29-rc3, if you still > have trouble with those, please let us know. >
Ok, I'm now running:
Linux nightmare 2.6.28.2-nhoyle #1 SMP Fri Jan 30 04:50:03 EST 2009 x86_64 Intel(R) Core(TM)2 Quad CPU Q9450 @ 2.66GHz GenuineIntel GNU/Linux
Initial conclusion is that whatever defects were corrected (non SCHED_IDLE specific defects that is), the newer kernel version does the trick. Video playback is as smooth as ever when running foldingathome at simple nice 19 priority.
I am not sure that I can perceive a difference so far in testing that versus using SCHED_IDLE. I will probably continue to use the latter anyhow, as that represents more accurately the semantics that I'm trying to achieve.
I had previously tried upgrading my kernel version in case that would fix it, but even the latest available kernels in the portage tree for Gentoo are older than 2.6.28.2. The 'stable' ones were all still 2.6.27. I have had some concerns about Gentoo as a distro for some time, but it still allows me more freedom and perfomance optimization than do most other distros. I'll leave that at that for now to avoid starting any religous wars over distros.
Once I downloaded and built the latest vanilla 2.6.28.2 sources from kernel.org though, everything seems improved, as mentioned above.
Thanks to each of you who responded for all the help. I will continue to experiment over the next week or so and provide feedback if I see anything further unusual, but so far things seem good.
-Nathanael
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