On Wed, 06 Mar 2024 17:45:04 -0800, Christoph Lameter (Ampere) wrote:
> Currently defconfig selects NR_CPUS=256, but some vendors (e.g. Ampere
> Computing) are planning to ship systems with 512 CPUs. So that all CPUs on
> these systems can be used with defconfig, we'd like to bump NR_CPUS to 512.
> Therefore this patch increases the default NR_CPUS from 256 to 512.
>
> As increasing NR_CPUS will increase the size of cpumasks, there's a fear that
> this might have a significant impact on stack usage due to code which places
> cpumasks on the stack. To mitigate that concern, we can select
> CPUMASK_OFFSTACK. As that doesn't seem to be a problem today with
> NR_CPUS=256, we only select this when NR_CPUS > 256.
>
> [...]
Applied to arm64 (for-next/misc), thanks!
I dropped the config entry and comment, replaced it with a select as per
Mark's suggestion.
[1/1] ARM64: Dynamically allocate cpumasks and increase supported CPUs to 512
https://git.kernel.org/arm64/c/0499a78369ad
--
Catalin
