Messages in this thread | | | From | Valentin Schneider <> | Subject | Re: [PATCH v2 0/5] cpumask: cleanup nr_cpu_ids vs nr_cpumask_bits mess | Date | Tue, 06 Sep 2022 16:45:37 +0100 |
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On 06/09/22 16:38, Peter Zijlstra wrote: > On Tue, Sep 06, 2022 at 01:06:47PM +0100, Valentin Schneider wrote: > >> #define nr_cpumask_bits nr_cpu_ids > > That assumes the CPU space is dense; is this so? That is, you can have 4 > CPUs while the highest cpu number is vastly larger than 4. > > It's uncommon, but not unheard of I think. ISTR some BIOSes leaving > holes in the CPU space when there were empty CPU sockets on the > motherboard.
I'd assume this would be visible in the cpu_possible_mask and thus be properly reflected in nr_cpu_ids. Otherwise that would already break with CONFIG_CPUMASK_OFFSTACK=y, I think.
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