Re: [stable] scheduler nice 19 versus 'idle' behavior / static low-priorityscheduling

[Brian Rogers]

Greg KH wrote:
> On Sat, Jan 31, 2009 at 10:08:13AM +0100, Mike Galbraith wrote:
>   
> > On Sat, 2009-01-31 at 06:38 +0100, Mike Galbraith wrote:
> >     
> > > On Fri, 2009-01-30 at 14:12 -0800, Brian Rogers wrote:
> > >       
> > > > Mike Galbraith wrote:
> > > >         
> > > > > On Fri, 2009-01-30 at 02:59 -0500, Nathanael Hoyle wrote:
> > > > >   
> > > > >           
> > > > > > I am running foldingathome under it at the moment, and it seems to be
> > > > > > improving the situation somewhat, but I still need/want to test with
> > > > > > Mike's referenced patches.
> > > > > >     
> > > > > >             
> > > > > You will most definitely encounter evilness running SCHED_IDLE tasks in
> > > > > a kernel without the SCHED_IDLE fixes.
> > > > >   
> > > > >           
> > > > Speaking of SCHED_IDLE fixes, is 
> > > > 6bc912b71b6f33b041cfde93ca3f019cbaa852bc going to be put into the next 
> > > > stable 2.6.28 release? Without it on 2.6.28.2, I can still produce 
> > > > minutes-long freezes with BOINC or other idle processes.
> > > >
> > > > With the above commit on top of 2.6.28.2 and also 
> > > > cce7ade803699463ecc62a065ca522004f7ccb3d, the problem is solved, though 
> > > > I assume cce7ad isn't actually required to fix that, and I can test that 
> > > > if desired.
> > > >         
> > > I think they both should go to stable, but dunno if they're headed that
> > > direction or not.
> > >
> > > One way to find out, CCs added.
> > >       
> > For those who may want to run SCHED_IDLE tasks in .27, I've integrated
> > and lightly tested the fixes required to do so.  One additional commit
> > was needed to get SCHED_IDLE vs nice 19 working right, namely f9c0b09.
> > Without that, SCHED_IDLE tasks received more CPU than nice 19 tasks.
> >
> > Since .27 is in long-term maintenance, I'd integrate into stable, but
> > that's not my decision.  Anyone who applies the below to their stable
> > kernel gets to keep all the pieces should something break ;-)
> >     
>
> I'm going to hold off and not do this, as it seems too risky.
>
> But thanks for the pointers, perhaps someone else will want to do this
> for their distro kernels if they have problems with this.
>   

Is this statement meant to apply to both 2.6.27 and 2.6.28, or just 2.6.27?

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