From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f171.google.com (mail-wi0-f171.google.com [209.85.212.171]) by kanga.kvack.org (Postfix) with ESMTP id 2F3E06B0031 for ; Tue, 3 Jun 2014 09:20:49 -0400 (EDT) Received: by mail-wi0-f171.google.com with SMTP id cc10so6526568wib.4 for ; Tue, 03 Jun 2014 06:20:48 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id gr5si32317572wjc.118.2014.06.03.06.20.42 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 03 Jun 2014 06:20:43 -0700 (PDT) Date: Tue, 3 Jun 2014 15:20:29 +0200 From: Michal Hocko Subject: Re: [patch 03/10] mm: memcontrol: retry reclaim for oom-disabled and __GFP_NOFAIL charges Message-ID: <20140603132029.GI1321@dhcp22.suse.cz> References: <1401380162-24121-1-git-send-email-hannes@cmpxchg.org> <1401380162-24121-4-git-send-email-hannes@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1401380162-24121-4-git-send-email-hannes@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: Andrew Morton , Hugh Dickins , Tejun Heo , Vladimir Davydov , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu 29-05-14 12:15:55, Johannes Weiner wrote: > There is no reason why oom-disabled and __GFP_NOFAIL charges should > try to reclaim only once when every other charge tries several times > before giving up. Make them all retry the same number of times. I have mentioned that already with the last iteration of the patch. This can make THP charges stall unnecessarily when the allocation could fall back to single page charges. MEM_CGROUP_RECLAIM_RETRIES * SWAP_CLUSTER_MAX + CHARGE_BATCH * CPUS reclaimed pages will not help for huge pages so multiple reclaims is just pointless waisting of time. I think you should just move the next patch in the series up and simply make the thp charge __GFP_NORETRY: diff --git a/mm/memcontrol.c b/mm/memcontrol.c index b3a6deed66d5..ba822c27a55b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3703,10 +3703,13 @@ int mem_cgroup_charge_anon(struct page *page, nr_pages <<= compound_order(page); VM_BUG_ON_PAGE(!PageTransHuge(page), page); /* - * Never OOM-kill a process for a huge page. The - * fault handler will fall back to regular pages. + * Never OOM-kill a process for a huge page. Also do not + * reclaim memcg too much because it wouldn't help the + * huge page charge anyway. + * The fault handler will fall back to regular pages. */ oom = false; + gfp_mask |= __GFP_NORETRY; } memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, nr_pages, oom); > Signed-off-by: Johannes Weiner > --- > mm/memcontrol.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 46b3e37542ad..e8d5075c081f 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2567,7 +2567,7 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg, > bool oom) > { > unsigned int batch = max(CHARGE_BATCH, nr_pages); > - int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES; > + int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; > struct mem_cgroup *mem_over_limit; > struct res_counter *fail_res; > unsigned long nr_reclaimed; > @@ -2639,6 +2639,9 @@ retry: > if (mem_cgroup_wait_acct_move(mem_over_limit)) > goto retry; > > + if (nr_retries--) > + goto retry; > + > if (gfp_mask & __GFP_NOFAIL) > goto bypass; > > @@ -2648,9 +2651,6 @@ retry: > if (!oom) > goto nomem; > > - if (nr_oom_retries--) > - goto retry; > - > mem_cgroup_oom(mem_over_limit, gfp_mask, get_order(batch)); > nomem: > if (!(gfp_mask & __GFP_NOFAIL)) > -- > 1.9.3 > -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org