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