Messages in this thread | | | Subject | Re: [PATCH RT] Fix RT balancing tasks pulling | From | Josh Triplett <> | Date | Tue, 31 Jul 2007 17:18:03 -0700 |
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On Tue, 2007-07-31 at 13:48 +0200, Sébastien Dugué wrote: > On Mon, 30 Jul 2007 14:50:34 -0700 Josh Triplett <josht@linux.vnet.ibm.com> wrote: > > On Tue, 2007-07-24 at 15:42 +0200, Sébastien Dugué wrote: > > > this one-liner fixes a bug in balance_rt_tasks() which sometimes manifests by > > > having a lower prio task being scheduled while a higher prio task is sitting > > > waiting on another runqueue. > > > > > > This is pretty hard to reproduce on low cpu count machines, for example, I > > > had to have sched_football run in a loop for ~38h before it failed on a dual HT > > > Xeon box. > > > > Very impressive find, and this does seem to improve things in some > > cases. > > > > However, with 2.6.22.1-rt8, which includes this patch, I still managed > > to get some failures after a few hours on an 8-way (quad dual-core) box. > > Preliminary results so far: > > 420 Final ball position: 0 > > 2 Final ball position: 1 > > > > Darn, I thought it was it :( > > I had a ~60h run on my box with the very same kernel without a single > failure.
I think you really need a box with more processors to reproduce these problems in a reasonable timeframe. Happy to test any patches you have to fix RT balancing; please let me know.
> Do you have any other user RT load running when those failures pop up?
Other than sched_football, I had sshd, bash, and GNU screen, theoretically all 100% idle (no input to read and no output to display).
- Josh Triplett
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