Re: [RFC] mm: get_mm_counter() get the total memory usage of the process

[David Hildenbrand]

On 22.03.24 16:11, Chen Taotao wrote:
> Currently, the get_mm_counter() function returns only the value of
> the process memory counter percpu_counter ->count record, ignoring
> the memory usage count maintained by each CPU in the
> percpu_counter->counters array, which leads to an error in obtaining
> the memory usage count of a process, especially when there are many
> CPU cores. counts, especially when there are many CPU cores.
>
> It is now possible to have get_mm_counter() get the memory count of a
> process by adding the memory counts maintained by each cpu, thus getting
> an accurate memory count of the process.
>
> This patch is an unofficial version that simply fixes the above problem,
> as I'm not sure if it makes sense to do so.

What is the effective change? Do you have any real examples where we can 
observe a real difference, so it's worth the churn?

On the other hand, doing the sum gets more expensive, do we care? How 
expensive is it?

Such a discussion should ideally be part of this change log.

"I'm not sure if it makes sense" -- you tell us, how did you come up 
with the idea? :)

--
Cheers,

David / dhildenb