Re: [patch] voluntary-preempt-2.6.8.1-P9

Lee Revell
2004-08-24T20:32:50Z

On Tue, 2004-08-24 at 13:43, K.R. Foley wrote:
> Ingo Molnar wrote:
> > * Scott Wood <scott@timesys.com> wrote:
> >
> >
> >>I have attached a port of the voluntary preempt patch to PPC and
> >>PPC64. The patch is against P7, but it applies against P8 as well.
> >
> >
> > thanks Scott, i've applied your patch to my tree - all the changes and
> > improvements look good (except for a small compilation problem on x86,
> > asm/time.h doesnt exist there - asm/rtc.h does). The resulting code
> > booted fine on an SMP and on a UP x86 system. I've uploaded -P9:
> >
> > http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.8.1-P9
> >
> > (there are no other changes in -P9.)
> >
> > Ingo
> > -
>
> ~254 usec latency seen in kswapd:
>
> http://www.cybsft.com/testresults/2.6.8.1-P9/latency_trace2.txt
>

I am able to generate unbounded latencies in kswapd by running `make
-j12' for any C++ program that uses KDE/Qt. The build will allocate all
available RAM, then all available swap, then the machine grinds to a
halt.

I am not sure this is solvable though. If you fire off a bunch of
processes that try to allocate way more memory than is physically
available then you will have worse problems than latency.

Lee