From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Davydov Subject: Re: [PATCH 7/8] mm: vmscan: report vmpressure at the level of reclaim activity Date: Thu, 22 Oct 2015 21:48:53 +0300 Message-ID: <20151022184852.GP18351@esperanza> References: <1445487696-21545-1-git-send-email-hannes@cmpxchg.org> <1445487696-21545-8-git-send-email-hannes@cmpxchg.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: "David S. Miller" , Andrew Morton , Michal Hocko , Tejun Heo , , , , To: Johannes Weiner Return-path: Content-Disposition: inline In-Reply-To: <1445487696-21545-8-git-send-email-hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org On Thu, Oct 22, 2015 at 12:21:35AM -0400, Johannes Weiner wrote: ... > @@ -2437,6 +2439,10 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc, > } > } > > + vmpressure(sc->gfp_mask, memcg, > + sc->nr_scanned - scanned, > + sc->nr_reclaimed - reclaimed); > + > /* > * Direct reclaim and kswapd have to scan all memory > * cgroups to fulfill the overall scan target for the > @@ -2454,10 +2460,6 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc, > } > } while ((memcg = mem_cgroup_iter(root, memcg, &reclaim))); > > - vmpressure(sc->gfp_mask, sc->target_mem_cgroup, > - sc->nr_scanned - nr_scanned, > - sc->nr_reclaimed - nr_reclaimed); > - > if (sc->nr_reclaimed - nr_reclaimed) > reclaimable = true; > I may be mistaken, but AFAIU this patch subtly changes the behavior of vmpressure visible from the userspace: w/o this patch a userspace process will only receive a notification for a memory cgroup only if *this* memory cgroup calls reclaimer; with this patch userspace notification will be issued even if reclaimer is invoked by any cgroup up the hierarchy. Thanks, Vladimir