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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,T_DKIMWL_WL_HIGH, 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 BD5D1C28CC3 for ; Tue, 4 Jun 2019 07:02:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9120E23AC4 for ; Tue, 4 Jun 2019 07:02:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559631754; bh=2hkWIsDCxMfQ4Vfe/EFO+MR3d5x4g545vzm5ZgeMp6g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=m/9zQYF8fTQy88ZKKR4G1ZK8OOoPWkvgolKsVyqGBpmus/5gQFFPZ8lqOlGQ+VGwp X0uRG8djHDCtsNwZVNWjJv8fDdBrR5X5tMaXHw+1I1FBW35GQ5q9Jo24dvibYSMbVd sHK8KOnetJ3Z0JMZJVvNqlZC18sB1UZ7VX922cjg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726949AbfFDHCd (ORCPT ); Tue, 4 Jun 2019 03:02:33 -0400 Received: from mx2.suse.de ([195.135.220.15]:48980 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726822AbfFDHCc (ORCPT ); Tue, 4 Jun 2019 03:02:32 -0400 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 58B31AE4E; Tue, 4 Jun 2019 07:02:30 +0000 (UTC) Date: Tue, 4 Jun 2019 09:02:28 +0200 From: Michal Hocko To: Minchan Kim Cc: Andrew Morton , linux-mm , LKML , linux-api@vger.kernel.org, Johannes Weiner , Tim Murray , Joel Fernandes , Suren Baghdasaryan , Daniel Colascione , Shakeel Butt , Sonny Rao , Brian Geffon , jannh@google.com, oleg@redhat.com, christian@brauner.io, oleksandr@redhat.com, hdanton@sina.com Subject: Re: [RFCv2 1/6] mm: introduce MADV_COLD Message-ID: <20190604070228.GD4669@dhcp22.suse.cz> References: <20190531064313.193437-1-minchan@kernel.org> <20190531064313.193437-2-minchan@kernel.org> <20190531084752.GI6896@dhcp22.suse.cz> <20190531133904.GC195463@google.com> <20190531140332.GT6896@dhcp22.suse.cz> <20190531143407.GB216592@google.com> <20190603071607.GB4531@dhcp22.suse.cz> <20190604042651.GC43390@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190604042651.GC43390@google.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 Tue 04-06-19 13:26:51, Minchan Kim wrote: > On Mon, Jun 03, 2019 at 09:16:07AM +0200, Michal Hocko wrote: [...] > > Right. But there is still the page cache reclaim. Is it expected that > > an explicitly cold memory doesn't get reclaimed because we have a > > sufficient amount of page cache (a very common case) and we never age > > anonymous memory because of that? > > If there are lots of used-once pages in file-LRU, I think there is no > need to reclaim anonymous pages because it needs bigger overhead due to > IO. It has been true for a long time in current VM policy. You are making an assumption which is not universally true. If I _know_ that there is a considerable amount of idle anonymous memory then I would really prefer if it goes to the swap rather than make a pressure on caching. Inactive list is not guaranteed to contain only used-once pages, right? Anyway, as already mentioned, we can start with a simpler implementation for now and explicitly note that pagecache biased reclaim is known to be a problem potentially. I am pretty sure somebody will come sooner or later and we can address the problem then with some good numbers to back the additional complexity. -- Michal Hocko SUSE Labs