Messages in this thread | | | Date | Thu, 02 Mar 2006 21:27:13 +1100 | From | Peter Williams <> | Subject | Re: 2.6.16-rc5-mm1 -- strange load balancing problems |
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I'm seeing some strange load balancing problems with this kernel. I don't think that they're due to the smpnice patches as I've applied them on a standard 2.6.15-rc5 kernel and the problem doesn't happen there.
The problem is (as I say) quite strange and (for me) very reproducible. I have two programs (aspin and gsmiley) which I use to produce CPU hard spinners for testing purposes. What I'm finding is that when I start several copies of aspin load balancing goes as expected but when I launch several copies of gsmiley they all go to the one CPU and stick there like glue. (The most obvious difference between the two programs is that aspin is just a command line tool while gsmiley is an X windows program that spins a simley face and reports its own assessment of the percentage of CPU it's getting.) The machine that I've seen this problem is a hyper threading Pentium 4 and I suspect that it may be due to the SCHED_MC changes which overlap SCHED_SMT a bit.
I'm trying to test this on a non hyper threading machine but the machine has crashed (different kernel) while doing the build. I'll resume this effort tomorrow but I thought that I should report the problem so that others could comment.
Peter PS SCHED_MC was configured in but I'll try it without tomorrow and report the results. -- Peter Williams pwil3058@bigpond.net.au
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