Messages in this thread | | | Date | Sun, 29 Aug 2004 14:53:41 +1000 | From | Peter Williams <> | Subject | Re: Scheduler fairness problem on 2.6 series (Attn: Nick Piggin and others) |
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spaminos-ker@yahoo.com wrote: > --- Peter Williams <pwil3058@bigpond.net.au> wrote: > >>The mode in which the scheduler was being used had all priority fiddling >>(except promotion) turned off so the tasks should have been just round >>robinning with each other. Also, the time outs are fairly rare (every >>few hours according to Nicolas's e-mail) and happen with several >>different schedulers (with ZAPHOD (the one being used by Nicolas) and >>Con's staircase schedulers having less problem than the vanilla >>scheduler) which is why I thought it might be something outside the >>scheduler. Perhaps it's something outside the kernel? >> > > > I can add to this that this problem occured on a variety of systems, single CPU > Pentium IIIs and 4s, Athlon, dual PIIIs ; > the one thing in common is that everything works fine on all those machines > with 2.4, but breaks with 2.5 (or redhat 2.4 kernel with some backported code).
I don't suppose you know what the backported code was? If you could provide a patch of the backport it might provide some clues.
> When I do the tests, the only thing I switch is the kernel and reboot. > > It's true that it could be something broken outside of the scheduling code > (like the way IRQ events are handled maybe, or the way signals are delivered). > > The one difference between the artificial test (from the original post) and the > real life test I do now, is that the real test combines disks I/O, network I/O > (TCP/IP and UDP) and several multithreaded processes. > Where things are kind of bad is that I am far from saturating the machine (the > load average is less than 2), but still some processes get those annoying > timeouts.
Peter -- Peter Williams pwil3058@bigpond.net.au
"Learning, n. The kind of ignorance distinguishing the studious." -- Ambrose Bierce
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