Re: [PATCH] mm: yield during swap prefetching

[Con Kolivas <kernel@kolivas.org>]

On Wed, 8 Mar 2006 01:18 pm, Lee Revell wrote:
> On Wed, 2006-03-08 at 13:12 +1100, Con Kolivas wrote:
> > On Wed, 8 Mar 2006 01:08 pm, Lee Revell wrote:
> > > On Wed, 2006-03-08 at 12:28 +1100, Con Kolivas wrote:
> > > > I can't distinguish between when cpu activity is important (game) and
> > > > when it is not (compile), and assuming worst case scenario and not
> > > > doing any swap prefetching is my intent. I could add cpu accounting
> > > > to prefetch_suitable() instead, but that gets rather messy and
> > > > yielding achieves the same endpoint.
> > >
> > > Shouldn't the game be running with RT priority or at least at a low
> > > nice value?
> >
> > No way. Games run nice 0 SCHED_NORMAL.
>
> Maybe this is a stupid/OT question (answer off list if you think so) but
> why not?  Isn't that the standard way of telling the scheduler that you
> have a realtime constraint?  It's how pro audio stuff works which I
> would think has similar RT requirements.
>
> How is the scheduler supposed to know to penalize a kernel compile
> taking 100% CPU but not a game using 100% CPU?

Because being a serious desktop operating system that we are (bwahahahaha) 
means the user should not have special privileges to run something as simple 
as a game. Games should not need special scheduling classes. We can always 
use 'nice' for a compile though. Real time audio is a completely different 
world to this. 

Cheers,
Con