[erlang-questions] VM using only 2 out of 8 schedulers available

Knut Nesheim <>
Wed Feb 15 17:53:28 CET 2012


Dear list,

>From time to time we see the VM using only some of the available
cores. Typically 2 or 4 out of 8 available cores will be busy, while
the others are not used at all. From 'top' and 'htop' we see only some
cores being used.

We are running the halfword emulator on 8 core machines and the VM is
correctly reporting the number of schedulers and the underlying
topology. The nodes are utilizing roughly 25% of each of the 8 cores
during normal operation.

This problem appeared again today and we still have the process
running if anyone has any ideas for how to debug the issue.

We are on Ubuntu 10.04 LTS, 2.6.32-342-ec2, 64bit, R14B04 with the
halfword emulator. The only NIF library we are using is jiffy.

Regards
Knut



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