Re: [ckrm-tech] [RFC][PATCH 5/7] UBC: kernel memory accounting (core)

[Kirill Korotaev <dev@sw.ru>]

Andi Kleen wrote:
> > I don't see any good way around that. For the page struct it is a
> > material issue, for the others its not a big deal providing we avoid
> > accounting dumb stuff like dentries.
> >
> > At the VM summit Linus suggested one option for user page allocation
> > tracking would be to track not per page but by block of pages (say the
> > 2MB chunks) and hand those out per container. That would really need the
> > defrag work though.
>
>
> One could always use a second set of arrays, mirroring mem_map
which one do you prefer:
- having a pointer on the struct page?
 kernels without resource accounting won't have this.

- having a mirroring mem_map?
 on i686 it is easy, but not sure about sparse mem
 or numa configurations.
 advantage: run-time configurable on boot time.
 disadvantage: much lower performance with accounting.

- address_space/anon_vma can be replaced with some kind of proxy object
 with 2 pointers - address_space and ub. however I don't see how it is
 better then a single ptr on page.

Thanks,
Kirill

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