Re: 2.6.8-rc2-mm2

[Con Kolivas]

Ingo Molnar writes:

> * Con Kolivas <kernel@xxxxxxxxxxx> wrote:
>
> > Ingo Molnar writes:
> >
> > Thanks for replying.
> >
> > >* Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote:
> > >
> > >>Also, basic interactivity in X is bad with the interactive sysctl set
> > >>to 0 (is X supposed to be at nice 0?), however fairness is bad when
> > >>interactive is 1. I'm not sure if this is an acceptable tradeoff - are
> > >>you planning to fix it?
> > >
> > >it also has clear interactivity problems when just running lots of CPU
> > >hogs even with the default interactive=1 compute=0 setting.
> >
> > Can you define them please? I haven't had any reported to me.
>
> sure: take a process that uses 85% of CPU time (and sleeps 15% of the
> time) if running on an idle system. Start just two of these hogs at
> normal priority. 2.6.8-rc2-mm2 becomes almost instantly unusable even
> over a text console: a single 'top' refresh takes ages, 'ls' displays
> one line per second or so. Start more of these and the system
> effectively locks up.

It's only if I physically try and create such a test application that I can 
reproduce it. I haven't found any real world load that does that - but of 
course that doesn't mean I should discount it. However, interactive mode off 
doesn't exhibit it and it should be easy enough to fix for interactive mode 
on. Thanks for pointing it out.

Cheers,
Con

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