Windows on HP ProLiant servers and number of logical cores

Windows on HP ProLiant servers and number of logical cores

posted by Jean-Francois Panisset on Oct. 28, 2016, 8 p.m. (1 day ago)

There's an obscure BIOS parameter on ProLiant servers which can cause some older Windows APIs to return only half the number of logical cores:

http://h20566.www2.hpe.com/hpsc/doc/public/display?sp4ts.oid=5379860&docId=emr_na-c04650594&docLocale=en_US

In particular this shows up in the %NUMBER_OF_PROCESSORS% environment variable being set wrong, and the Python psutil module.

Unless you have 18 core CPUs, setting the BIOS parameter "NUMA Group Size Optimization" to "Flat" instead of "Clustered" will solve the problem.

Turns out that HP has a useful PowerShell module for manipulating BIOS parameters:

https://www.hpe.com/us/en/product-catalog/detail/pip.5440657.html#

but unfortunately that particular param is not exposed through that module.

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In particular this shows up in the %NUMBER_OF_PROCESSORS% environment variable being set wrong, and the Python psutil module.

Unless you have 18 core CPUs, setting the BIOS parameter "NUMA Group Size Optimization" to "Flat" instead of "Clustered" will solve the problem.

Turns out that HP has a useful PowerShell module for manipulating BIOS parameters:

https://www.hpe.com/us/en/product-catalog/detail/pip.5440657.html#

but unfortunately that particular param is not exposed through that module.