Re: [PATCH 3/3] dcache: account external names as indirectly reclaimable memory

[Roman Gushchin <guro@fb.com>]

On Mon, Apr 16, 2018 at 01:41:44PM +0200, Michal Hocko wrote:
> On Fri 13-04-18 10:37:16, Johannes Weiner wrote:
> > On Fri, Apr 13, 2018 at 04:28:21PM +0200, Michal Hocko wrote:
> > > On Fri 13-04-18 16:20:00, Vlastimil Babka wrote:
> > > > We would need kmalloc-reclaimable-X variants. It could be worth it,
> > > > especially if we find more similar usages. I suspect they would be more
> > > > useful than the existing dma-kmalloc-X :)
> > > 
> > > I am still not sure why __GFP_RECLAIMABLE cannot be made work as
> > > expected and account slab pages as SLAB_RECLAIMABLE
> > 
> > Can you outline how this would work without separate caches?
> 
> I thought that the cache would only maintain two sets of slab pages
> depending on the allocation reuquests. I am pretty sure there will be
> other details to iron out and maybe it will turn out that such a large
> portion of the chache would need to duplicate the state that a
> completely new cache would be more reasonable. Is this worth exploring
> at least? I mean something like this should help with the fragmentation
> already AFAIU. Accounting would be just free on top.

IMO, this approach is much better than duplicating all kmalloc caches.
It's definitely has to be explored and discussed.

Thank you!