Re: Fwd: Re: slablru for 2.5.32-mm1

Andrew Morton
2002-09-02T20:02:11Z

Ed Tomlinson wrote:
>
> ...
> The pages which back slab objects may be manually marked as referenced
> via kmem_touch_page(), which simply sets PG_referenced. It _could_ use
> mark_page_accessed(), but doesn't. So slab pages will always remain on
> the inactive list.
>
> --
> Since shrinking a slab is a much lower cost operation than a swap we keep
> the slab pages in inactive where they age faster. Note I did test with slabs
> following the normal active/inactive cycle - we swapped more.
> --

It worries me that we may be keeping a large number of unfreeable
slab pages on the inactive list. These will churn around creating
extra work, but more significantly they will revent refill_inactive
from bringing down really-reclaimable pages.

> ...
> Actually the BUG_ON conversion were done by Craig Kulesa. It would be a
> good idea to credit him with the initial port to 2.5 - he did to the work.

OK.