Re: 2.6.21-rc3-mm1 RSDL results

[Con Kolivas <kernel@kolivas.org>]

On Saturday 10 March 2007 08:39, Matt Mackall wrote:
> On Sat, Mar 10, 2007 at 08:19:18AM +1100, Con Kolivas wrote:
> > On Saturday 10 March 2007 08:07, Con Kolivas wrote:
> > > On Saturday 10 March 2007 07:46, Matt Mackall wrote:
> > > > My suspicion is the problem lies in giving too much quanta to
> > > > newly-started processes.
> > >
> > > Ah that's some nice detective work there. Mainline does some rather
> > > complex accounting on sched_fork including (possibly) a whole timer
> > > tick which rsdl does not do. make forks off continuously so what you
> > > say may well be correct. I'll see if I can try to revert to the
> > > mainline behaviour in sched_fork (which was obviously there for a
> > > reason).
> >
> > Wow! Thanks Matt. You've found a real bug too. This seems to fix the qemu
> >  misbehaviour and bitmap errors so far too! Now can you please try this
> > to see if it fixes your problem?
>
> Sorry, it's about the same. I now suspect an accounting glitch involving
> pipe wake-ups.
>
> 5x memload: good
> 5x execload: good
> 5x forkload: good
> 5 parallel makes: mostly good
> make -j 5: bad
>
> So what's different between makes in parallel and make -j 5? Make's
> job server uses pipe I/O to control how many jobs are running.

Hmm it must be those deep pipes again then. I removed any quirks testing for 
those from mainline as I suspected it would be ok. Guess I"m wrong.

-- 
-ck