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seen Apr 5 '12 at 17:14

Dec
5
awarded  Popular Question
Apr
5
comment Linux Scheduler (not using all cores on multi-core machine) RHEL6
Yes, it's a typical Xeon server. 2 physical xeon processors (hyper-threaded).
Apr
5
comment Linux Scheduler (not using all cores on multi-core machine) RHEL6
I didn't pin the processes at all. I can manually fix the problem by using taskset and then pinning the processes to different CPUs (then I see each process running at 100%), but that's obviously not a solution. The problem seems to be with the CPU load balancer, where it's not moving processes to less busy CPUs. I've run all kinds of other test variants (where each process also sleeps every once in a while between it's spins, but it still seems to be stuck on the CPU it was given at the start..)
Apr
5
comment Linux Scheduler (not using all cores on multi-core machine) RHEL6
Why would results vary if I have much more than 4 cores (and yes, this server has a lot of cores). When I run stress, I also see some bizarre behavior. For example, running "stress -c 2 -t 60" three times it sometimes works correctly (6 processes running at 100%). But sometimes they're clustered (100%, 100%, 100%, 33%, 33%, 33%, for example). When I do "stress -c 4 -t 60" so far every time it's been 4 processes at 100%. But "stress -c 6 -t 60" has never worked (it's always split somehow with other CPUs sitting idle)...
Apr
5
comment Linux Scheduler (not using all cores on multi-core machine) RHEL6
The problem started with actual programs doing actually work where many were all assigned the same CPU and they were stuck (so some CPUs were at 100% while many other CPUs were completely idle). I then simplified it to this test program. Even when I change the test program to do actual work I see the same problem.
Apr
4
awarded  Student
Apr
4
asked Linux Scheduler (not using all cores on multi-core machine) RHEL6