Date: Fri, 2 Jul 2021 14:29:37 +0100 From: Vincent Donnefort <vincent.donnefort@....com> To: jyknight@...gle.com, musl@...ts.openwall.com Subject: Re: Re: [PATCH v2] sysconf: add _SC_NPROCESSORS_CONF support Hi James, Here's a new thread as I never received your previous email and I just noticed the answer today. I'm not sure I understand why I can't use "present". As per the kernel documentation: possible: CPUs that have been allocated resources and can be brought online if they are present. [cpu_possible_mask] present: CPUs that have been identified as being present in the system. [cpu_present_mask] In this example, the NR_CPUS config option is 128, but the kernel was started with possible_cpus=144. There are 4 CPUs in the system and cpu2 was manually taken offline (and is the only CPU that can be brought online.):: kernel_max: 127 offline: 2,4-127,128-143 online: 0-1,3 possible: 0-127 present: 0-3 So indeed I could use "possible"... but there's a chance the two masks won't be equal, and the sysfs entries are matching "present", not "possible". "possible" is the CPUs that have allocated resources and can be physically added to the system. "present" is the CPUs that are known as physically present but might be offline. -- Vincent
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