On Mon, 2019-01-28 at 11:54 -0800, Andrew Morton wrote:
> On Mon, 28 Jan 2019 14:35:35 -0500 Rik van Riel <riel@xxxxxxxxxxx>
> wrote:
>
> > /*
> > * Make sure we apply some minimal pressure on default priority
> > - * even on small cgroups. Stale objects are not only consuming
> > memory
> > + * even on small cgroups, by accumulating pressure across
> > multiple
> > + * slab shrinker runs. Stale objects are not only consuming
> > memory
> > * by themselves, but can also hold a reference to a dying
> > cgroup,
> > * preventing it from being reclaimed. A dying cgroup with all
> > * corresponding structures like per-cpu stats and kmem caches
> > * can be really big, so it may lead to a significant waste of
> > memory.
> > */
> > - delta = max_t(unsigned long long, delta, min(freeable,
> > batch_size));
> > + if (!delta) {
> > + shrinker->small_scan += freeable;
> > +
> > + delta = shrinker->small_scan >> priority;
> > + shrinker->small_scan -= delta << priority;
> > +
> > + delta *= 4;
> > + do_div(delta, shrinker->seeks);
>
> What prevents shrinker->small_scan from over- or underflowing over
> time?
We only go into this code path if
delta >> DEF_PRIORITY is zero.
That is, freeable is smaller than 4096.
> I'll add this:
> whitespace fixes, per Roman
Awesome, thank you!
--
All Rights Reversed.
Attachment:
signature.asc
Description: This is a digitally signed message part
