From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f197.google.com (mail-pf0-f197.google.com [209.85.192.197]) by kanga.kvack.org (Postfix) with ESMTP id CF8D46B0033 for ; Wed, 27 Sep 2017 10:10:22 -0400 (EDT) Received: by mail-pf0-f197.google.com with SMTP id r83so23401278pfj.5 for ; Wed, 27 Sep 2017 07:10:22 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id b6sor1544942plx.66.2017.09.27.07.10.21 for (Google Transport Security); Wed, 27 Sep 2017 07:10:21 -0700 (PDT) Date: Wed, 27 Sep 2017 23:10:08 +0900 From: Minchan Kim Subject: Re: [PATCH] mm, swap: Make VMA based swap readahead configurable Message-ID: <20170927141008.GA1278@bgram> References: <20170921013310.31348-1-ying.huang@intel.com> <20170926132129.dbtr2mof35x4j4og@dhcp22.suse.cz> <20170927050401.GA715@bbox> <20170927074835.37m4dclmew5ecli2@dhcp22.suse.cz> <20170927080432.GA1160@bbox> <20170927083512.dydqlqezh5polggb@dhcp22.suse.cz> <20170927131511.GA338@bgram> <20170927132241.tshup6kcwe5pcxek@dhcp22.suse.cz> <20170927134117.GB338@bgram> <20170927135034.yatxlhvunawzmcar@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170927135034.yatxlhvunawzmcar@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: "Huang, Ying" , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Johannes Weiner , Rik van Riel , Shaohua Li , Hugh Dickins , Fengguang Wu , Tim Chen , Dave Hansen On Wed, Sep 27, 2017 at 03:50:34PM +0200, Michal Hocko wrote: > On Wed 27-09-17 22:41:17, Minchan Kim wrote: > > On Wed, Sep 27, 2017 at 03:22:41PM +0200, Michal Hocko wrote: > [...] > > > simply cannot disable swap readahead when page-cluster is 0? > > > > That's was what I want really but Huang want to use two readahead > > algorithms in parallel so he wanted to keep two separated disable > > knobs. > > If it breaks existing and documented behavior then it is a clear > regression and it should be fixed. I do not see why this should be > disputable at all. Indeed but Huang doesn't think so. He has thought it's not a regression. Frankly speaking, I'm really bored of discussing with it. https://marc.info/?l=linux-mm&m=150526413319763&w=2 So I passed the decision to Andrew. http://lkml.kernel.org/r/<20170913014019.GB29422@bbox> The config option idea is compromise approach although I don't like it and still believe it's simple clear *regression* so 0 page-cluster should keep the swap readahead disabled. > > Working around an issue with a config option sounds like the wrong way > to go because those who cannot do that unconditionally would still see a > regression. I absolutely agree but as I said, the discussion was not productive even though I did best effort to persuade. That's all for my side as contributor/reviewer. Decision is up to maintainer. ;-) Thanks for the opinion, Michal. -- 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