Re: [RFC PATCH] futex: Dynamically allocate futex_queues depending on nr_node_ids

[K Prateek Nayak <kprateek.nayak@amd.com>]

Hello Sebastian,

On 2/24/2026 4:43 PM, Sebastian Andrzej Siewior wrote:
> My question was initially is 1024 for max-nodes something that people
> really use. It was introduced as of
> 	https://lore.kernel.org/all/alpine.DEB.2.00.1003101537330.30724@chino.kir.corp.google.com/
> 
> but it looks odd. It might just one or two machines which are left :)

I have it on good faith that some EPYC user on distro kernels turn on
"L3 as NUMA" option which currently results into 32 NUMA nodes on our
largest configuration.

Adding a little bit more margin for CXL nodes should make even
CONFIG_NODES_SHIFT=6 pretty sane default for most real-word configs.
I don't think we can go more than 10 or so CXL nodes considering the
number of PCIe lanes unless there are more creative ways to attach
tiered memory that appear as a NUMA node.

I'm not sure if Intel has similar crazy combination but NODES_SHIFT=6
can accommodate (16 socket * SNC-3) + up to 16 CXL nodes so it should
be fine for most distro users too?

-- 
Thanks and Regards,
Prateek