[Intel-wired-lan] [PATCH v4] ixgbe: let the xdpdrv work with more than 64 cpus

Eric Dumazet eric.dumazet at gmail.com
Thu Aug 26 18:19:35 UTC 2021

On 8/26/21 10:03 AM, Jason Xing wrote:

> Honestly, I'm a little confused right now. @nr_cpu_ids is the fixed
> number which means the total number of cpus the machine has.
> I think, using @nr_cpu_ids is safe one way or the other regardless of
> whether the cpu goes offline or not. What do you think?

More exactly, nr_cpu_ids is the max number cpu id can reach,
even in presence of holes.

I think that most/many num_online_cpus() in drivers/net are simply broken
and should be replaced by nr_cpu_ids.

The assumptions of cpus being nicely numbered from [0 to X-1],
with X==num_online_cpus() is wrong.

Same remark for num_possible_cpus(), see commit
88d4f0db7fa8 ("perf: Fix alloc_callchain_buffers()") for reference.

More information about the Intel-wired-lan mailing list