Re: [PATCH v2 4/6] slab: add SLAB_ACCOUNT flag

Vladimir Davydov
2015-11-11T16:07:37Z

On Wed, Nov 11, 2015 at 10:54:50AM -0500, Tejun Heo wrote:
> Hello,
>
> On Tue, Nov 10, 2015 at 09:54:01PM +0300, Vladimir Davydov wrote:
> > > Am I correct in thinking that we should eventually be able to removed
> > > __GFP_ACCOUNT and that only caches explicitly marked with SLAB_ACCOUNT
> > > would need to be handled by kmemcg?
> >
> > Don't think so, because sometimes we want to account kmalloc.
>
> I'm kinda skeptical about that because if those allocations are
> occassional by nature, we don't care and if there can be a huge number
> of them, splitting them into a separate cache makes sense. I think it
> makes sense to pin down exactly which caches are memcg managed. That
> has the potential to simplify the involved code path and shave off a
> small bit of hot path overhead.

What about external_name allocation in __d_alloc? Is it occasional?
Depends on the workload I guess. Can we create a separate cache for it?
No, because its size is variable. There are other things like that, e.g.
pipe_buffer array.

Thanks,
Vladimir