Messages in this thread | | | Date | Fri, 03 Mar 2006 09:23:41 +1100 | From | Peter Williams <> | Subject | Re: 2.6.16-rc5-mm1 -- strange load balancing problems |
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Peter Williams wrote: > 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.
Configuring SCHED_MC to "no" causes this problem to go away.
Peter -- Peter Williams pwil3058@bigpond.net.au
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