[PATCH v6 2/3] percpu: add PERCPU_ATOM_SIZE for a generic percpu area setup

[Christoph Lameter]

On Sun, 1 Nov 2015, Jungseok Lee wrote:

> There is no room to adjust 'atom_size' now when a generic percpu area
> is used. It would be redundant to write down an architecture-specific
> setup_per_cpu_areas() in order to only change the 'atom_size'. Thus,
> this patch adds a new definition, PERCPU_ATOM_SIZE, which is PAGE_SIZE
> by default. The value could be updated if needed by architecture.

What is atom_size? Why would you want a difference allocation size here?
The percpu area is virtually mapped regardless. So you will have
contiguous addresses even without atom_size.