On Fri, Aug 31, 2018 at 05:15:39PM -0400, Rik van Riel wrote:
> On Fri, 2018-08-31 at 13:34 -0700, Roman Gushchin wrote:
>
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index fa2c150ab7b9..c910cf6bf606 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -476,6 +476,10 @@ static unsigned long do_shrink_slab(struct
> > shrink_control *shrinkctl,
> > delta = freeable >> priority;
> > delta *= 4;
> > do_div(delta, shrinker->seeks);
> > +
> > + if (delta == 0 && freeable > 0)
> > + delta = min(freeable, batch_size);
> > +
> > total_scan += delta;
> > if (total_scan < 0) {
> > pr_err("shrink_slab: %pF negative objects to delete
> > nr=%ld\n",
>
> I agree that we need to shrink slabs with fewer than
> 4096 objects, but do we want to put more pressure on
> a slab the moment it drops below 4096 than we applied
> when it had just over 4096 objects on it?
>
> With this patch, a slab with 5000 objects on it will
> get 1 item scanned, while a slab with 4000 objects on
> it will see shrinker->batch or SHRINK_BATCH objects
> scanned every time.
>
> I don't know if this would cause any issues, just
> something to ponder.
Hm, fair enough. So, basically we can always do
delta = max(delta, min(freeable, batch_size));
Does it look better?
>
> If nobody things this is a problem, you can give the
> patch my:
>
> Acked-by: Rik van Riel <riel@xxxxxxxxxxx>
>
Thanks!
