From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751757AbdE3MYm (ORCPT ); Tue, 30 May 2017 08:24:42 -0400 Received: from mx2.suse.de ([195.135.220.15]:54935 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751322AbdE3MYk (ORCPT ); Tue, 30 May 2017 08:24:40 -0400 Date: Tue, 30 May 2017 14:24:36 +0200 From: Michal Hocko To: Roman Gushchin Cc: Balbir Singh , Johannes Weiner , Vladimir Davydov , kernel-team@fb.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: bump PGSTEAL*/PGSCAN*/ALLOCSTALL counters in memcg reclaim Message-ID: <20170530122436.GE7969@dhcp22.suse.cz> References: <1496062901-21456-1-git-send-email-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1496062901-21456-1-git-send-email-guro@fb.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 29-05-17 14:01:41, Roman Gushchin wrote: > Historically, PGSTEAL*/PGSCAN*/ALLOCSTALL counters were used to > account only for global reclaim events, memory cgroup targeted reclaim > was ignored. > > It doesn't make sense anymore, because the whole reclaim path > is designed around cgroups. Also, per-cgroup counters can exceed the > corresponding global counters, what can be confusing. The whole reclaim is designed around cgroups but the source of the memory pressure is different. I agree that checking global_reclaim() for PGSTEAL_KSWAPD doesn't make much sense because we are _always_ in the global reclaim context but counting ALLOCSTALL even for targetted memcg reclaim is more confusing than helpful. We usually consider this counter to see whether the kswapd catches up with the memory demand and the global direct reclaim is indicator it doesn't. The similar applies to other counters as well. So I do not think this is correct. What is the problem you are trying to solve here anyway. > So, make PGSTEAL*/PGSCAN*/ALLOCSTALL counters reflect sum of any > reclaim activity in the system. > > Signed-off-by: Roman Gushchin > Cc: Balbir Singh > Cc: Michal Hocko > Cc: Johannes Weiner > Cc: Vladimir Davydov > Cc: kernel-team@fb.com > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > --- > mm/vmscan.c | 15 +++++---------- > 1 file changed, 5 insertions(+), 10 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 7c2a36b..77253b1 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1765,13 +1765,11 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, > reclaim_stat->recent_scanned[file] += nr_taken; > > if (current_is_kswapd()) { > - if (global_reclaim(sc)) > - __count_vm_events(PGSCAN_KSWAPD, nr_scanned); > + __count_vm_events(PGSCAN_KSWAPD, nr_scanned); > count_memcg_events(lruvec_memcg(lruvec), PGSCAN_KSWAPD, > nr_scanned); > } else { > - if (global_reclaim(sc)) > - __count_vm_events(PGSCAN_DIRECT, nr_scanned); > + __count_vm_events(PGSCAN_DIRECT, nr_scanned); > count_memcg_events(lruvec_memcg(lruvec), PGSCAN_DIRECT, > nr_scanned); > } > @@ -1786,13 +1784,11 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, > spin_lock_irq(&pgdat->lru_lock); > > if (current_is_kswapd()) { > - if (global_reclaim(sc)) > - __count_vm_events(PGSTEAL_KSWAPD, nr_reclaimed); > + __count_vm_events(PGSTEAL_KSWAPD, nr_reclaimed); > count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_KSWAPD, > nr_reclaimed); > } else { > - if (global_reclaim(sc)) > - __count_vm_events(PGSTEAL_DIRECT, nr_reclaimed); > + __count_vm_events(PGSTEAL_DIRECT, nr_reclaimed); > count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_DIRECT, > nr_reclaimed); > } > @@ -2828,8 +2824,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, > retry: > delayacct_freepages_start(); > > - if (global_reclaim(sc)) > - __count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1); > + __count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1); > > do { > vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup, > -- > 2.7.4 > -- Michal Hocko SUSE Labs