Re: [PATCH] Hugepages should be accounted as unevictable pages.

KAMEZAWA Hiroyuki
2009-06-23T06:08:14Z

On Mon, 22 Jun 2009 22:54:01 -0700
Alok Kataria <akataria@vmware.com> wrote:

> > >
> > > I don't have any strong oppose reason, but I also don't have any strong
> > > agree reason.
> > >
> > I think "don't include Hugepage" is sane. Hugepage is something _special_, now.
> >
> Kamezawa-san,
>
> I agree that hugepages are special in the sense that they are
> implemented specially and don't actually reside on the LRU like any
> other locked memory. But, both of these memory types (mlocked and
> hugepages) are actually unevictable and can't be reclaimed back, so i
> don't see a reason why should accounting not reflect that.
>

I bet we should rename "Unevictable" to "Mlocked" or "Pinned" rather than
take nr_hugepages into account. I think this "Unevictable" in meminfo means
- pages which are evictable in their nature (because in LRU) but a user pinned it -

How about rename "Unevictable" to "Pinned" or "Locked" ?
(Mlocked + locked shmem's + ramfs?)

We have other "unevictable" pages other than Hugepage anyway.
- page table
- some slab
- kernel's page
- anon pages in swapless system
etc...

BTW, I use following calculation for quick check if I want all "Unevicatable" pages.

Unevictable = Total - (Active+Inactive) + (50-70%? of slab)

This # of is not-reclaimable memory.

Thanks,
-Kame

> Thanks,
> Alok
>
> > Thanks,
> > -Kame
> >
>
>