From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 15428C04EB9 for ; Mon, 3 Dec 2018 11:56:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D2F80206B7 for ; Mon, 3 Dec 2018 11:56:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D2F80206B7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726443AbeLCL5d (ORCPT ); Mon, 3 Dec 2018 06:57:33 -0500 Received: from mx2.suse.de ([195.135.220.15]:60108 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725975AbeLCL5d (ORCPT ); Mon, 3 Dec 2018 06:57:33 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 9D867AC66; Mon, 3 Dec 2018 11:56:46 +0000 (UTC) Date: Mon, 3 Dec 2018 12:56:46 +0100 From: Michal Hocko To: Xunlei Pang Cc: Roman Gushchin , Johannes Weiner , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 2/3] mm/vmscan: Enable kswapd to reclaim low-protected memory Message-ID: <20181203115646.GP31738@dhcp22.suse.cz> References: <20181203080119.18989-1-xlpang@linux.alibaba.com> <20181203080119.18989-2-xlpang@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181203080119.18989-2-xlpang@linux.alibaba.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 03-12-18 16:01:18, Xunlei Pang wrote: > There may be cgroup memory overcommitment, it will become > even common in the future. > > Let's enable kswapd to reclaim low-protected memory in case > of memory pressure, to mitigate the global direct reclaim > pressures which could cause jitters to the response time of > lantency-sensitive groups. Please be more descriptive about the problem you are trying to handle here. I haven't actually read the patch but let me emphasise that the low limit protection is important isolation tool. And allowing kswapd to reclaim protected memcgs is going to break the semantic as it has been introduced and designed. > > Signed-off-by: Xunlei Pang > --- > mm/vmscan.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 62ac0c488624..3d412eb91f73 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -3531,6 +3531,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) > > count_vm_event(PAGEOUTRUN); > > +retry: > do { > unsigned long nr_reclaimed = sc.nr_reclaimed; > bool raise_priority = true; > @@ -3622,6 +3623,13 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) > sc.priority--; > } while (sc.priority >= 1); > > + if (!sc.nr_reclaimed && sc.memcg_low_skipped) { > + sc.priority = DEF_PRIORITY; > + sc.memcg_low_reclaim = 1; > + sc.memcg_low_skipped = 0; > + goto retry; > + } > + > if (!sc.nr_reclaimed) > pgdat->kswapd_failures++; > > -- > 2.13.5 (Apple Git-94) > -- Michal Hocko SUSE Labs