Messages in this thread | | | Date | Wed, 14 Jan 2009 06:31:06 +0100 | From | Ingo Molnar <> | Subject | Re: [BUG] How to get real-time priority using idle priority |
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* Mike Galbraith <efault@gmx.de> wrote:
> On Tue, 2009-01-13 at 03:58 +0100, Mike Galbraith wrote: > > On Mon, 2009-01-12 at 17:05 -0800, Brian Rogers wrote: > > > > I'll try Mike's "more complete" patch on top of 2.6.29-rc1 and see what > > > that does. > > > > Don't bother. I just tried a SCHED_IDLE make -j8 and had character > > repeats while typing. Must be another spot. > > Hrmph, what an annoying problem. The below works pretty well, but > _still_ has latency problems in some circumstances. > > The more I look at this, the more I think these guys _really_ want to be > a separate class. The problem is the incredible rate of min_vruntime > advancement creating absurdly huge spreads. > > Hm, maybe I could advance min_vruntime at nice 0 when these guys are > running, only advance their vruntime at warp 512, but that seems awfully > hackish. If they were a separate class, they could use the full nice > spectrum instead of being merely mega-nice.
A separate class has its own set of problems: starvation, etc.
What about increasing the weight of SCHED_IDLE tasks from 1 to 2 or 3? That still makes them mega-nice (which is more than enough), but should make the math a lot less borderline.
Ingo
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