Re: 2.6.0-testX - strange scheduling(?) problem

[Nick Piggin]

Murray J. Root wrote:

> On Wed, Sep 17, 2003 at 03:22:41PM +1000, Nick Piggin wrote:
>
> > Murray J. Root wrote:
> >
> >
> > > P4 2G
> > > 1G PC2700 RAM
> > > GF2 GTS video (nv drivers, not nvidia)
> > >
> > > In all 2.6.0-test versions (1-5) I get very odd issues when using 
> > > cpu+memory
> > > intense apps. Using POV-Ray 3.5, for example:
> > > When I render an image I get about 15k pixels per second and the system is
> > > usable and responsive in other apps, most of the time.
> > > About 20% of the time the pixels-per-second is only 3k, the system is at
> > > nearly a standstill, and other apps barely function.
> > > I've tested it many times using the exact same image and the behavior is
> > > very consistent. Other apps do the same, but since I can't get a consistent
> > > starting state with them, I used POV-Ray for the testing.
> > > The slowdown is so bad that the screen can take as long as 2 seconds to 
> > > refresh, opening a term can take as much as 15 seconds.
> > > Stopping the render and restarting it fixes it about 1/2 the time. Stopping
> > > the render and switching to another app, then restarting the render fixes
> > > it about 1/2 the time. Enough stop & restarts always fixes it eventually.
> > > There doesn't appear to be any memory leakage, and the system isn't going
> > > into swap. Top shows the same numbers in all cases. Time of day, other 
> > > apps running, etc. makes no difference.
> > Hi Murray,
> > Thanks for reporting this. Its a very important issue. Would you please
> > try this patch:
> > http://ck.kolivas.org/patches/2.6/2.6.0-test5/patch-test5-O20int
> > on 2.6.0-test5, and report your results.
> >
> > If you get time, or if the above still has problems, you could try
> > http://www.kerneltrap.org/~npiggin/v15/sched-rollup-v15.gz
> > as well. Give priority to the first patch though, please.
>
> Using the first patch either fixed it or made it so rare I haven't seen it
> in 4 hours of testing.
> One side-effect - rendering seems to take about 20% longer, and top shows
> X using 20-25% cpu while rendering. Prior to 2.6.0-test[1-5] X never got
> up past 5% and generally hung around less than 1%.
> But user-feel is *much* better. No delays or "hangs" while typing or clicking
> even while running two renders at the same time.

CCing to the list. Sounds good. The longer rendering seems to be pretty
well in line with the CPU X is using. This is obviously fine and
desired. Thanks Murray, and good news, this patch will be included in
test6 as far as I can see.


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