Hi Greg,
Thanks for taking a look!
On Tue, Feb 12, 2013 at 10:42:51PM -0800, Greg Thelen wrote:
[...]
> > +static unsigned long vmpressure_calc_level(unsigned int win,
> > + unsigned int s, unsigned int r)
>
> Should seems like the return type of this function should be enum
> vmpressure_levels? If yes, then the 'return 0' below should be
> VMPRESSURE_LOW. And it would be nice if there was a little comment
> describing the meaning of the win, s, and r parameters. The "We
> calculate ..." comment below makes me think that win is the number of
> pages scanned, which makes me wonder what the s param is.
Got it, will make it clearer.
[...]
> > +static bool vmpressure_event(struct vmpressure *vmpr,
> > + unsigned long s, unsigned long r)
> > +{
> > + struct vmpressure_event *ev;
> > + int level = vmpressure_calc_level(vmpressure_win, s, r);
> > + bool signalled = 0;
> s/bool/int/
Um... I surely can do this, but why do you think it is a good idea?
> > +
> > + mutex_lock(&vmpr->events_lock);
> > +
> > + list_for_each_entry(ev, &vmpr->events, node) {
> > + if (level >= ev->level) {
> > + eventfd_signal(ev->efd, 1);
> > + signalled++;
> > + }
> > + }
> > +
> > + mutex_unlock(&vmpr->events_lock);
> > +
> > + return signalled;
[...]
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -1982,6 +1982,10 @@ static void shrink_zone(struct zone *zone, struct
> > scan_control *sc)
> > }
> > memcg = mem_cgroup_iter(root, memcg, &reclaim);
> > } while (memcg);
> > +
> > + vmpressure(sc->gfp_mask, sc->target_mem_cgroup,
> > + sc->nr_scanned - nr_scanned, nr_reclaimed);
>
> (sc->nr_scanned - nr_scanned) is the number of pages scanned in above
> while loop but nr_reclaimed is the starting position of the reclaim
> counter before the loop. It seems like you want:
> vmpressure(sc->gfp_mask, sc->target_mem_cgroup,
> sc->nr_scanned - nr_scanned,
> sc->nr_reclaimed - nr_reclaimed);
Yeah, right you are. There actually was a merge conflict when I rebased my
patch onto linux-next, and it seems that I overlooked that the logic has
changed. So we might get a bit distorted pressure because of that.
Thanks for catching this!
Anton
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