From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id E28186B0038 for ; Tue, 26 Sep 2017 07:54:26 -0400 (EDT) Received: by mail-pf0-f199.google.com with SMTP id y77so17973772pfd.2 for ; Tue, 26 Sep 2017 04:54:26 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id h28si5525141pfj.518.2017.09.26.04.54.25 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 26 Sep 2017 04:54:25 -0700 (PDT) Date: Tue, 26 Sep 2017 13:54:23 +0200 From: Michal Hocko Subject: Re: [PATCH v3] mm: introduce validity check on vm dirtiness settings Message-ID: <20170926115423.wdnctuqtxbhpdidx@dhcp22.suse.cz> References: <1505861015-11919-1-git-send-email-laoar.shao@gmail.com> <20170926102532.culqxb45xwzafomj@dhcp22.suse.cz> <20170926112656.tbu7nr2lxdqt5rft@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Yafang Shao Cc: Jan Kara , akpm@linux-foundation.org, Johannes Weiner , vdavydov.dev@gmail.com, jlayton@redhat.com, nborisov@suse.com, Theodore Ts'o , mawilcox@microsoft.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Tue 26-09-17 19:45:45, Yafang Shao wrote: > 2017-09-26 19:26 GMT+08:00 Michal Hocko : > > On Tue 26-09-17 19:06:37, Yafang Shao wrote: [...] > >> Anyway, there's no document on that direct limits should not less than > >> background limits. > > > > Then improve the documentation. > > I have improved the kernel documentation as well, in order to make it > more clear for the newbies. Why do we need to update the code then? > >> > To be honest I am not entirely sure this is worth the code and the > >> > future maintenance burden. > >> I'm not sure if this code is a burden for the future maintenance, but > >> I think that if we don't introduce this code it is a burden to the > >> admins. > > > > anytime we might need to tweak background vs direct limit we would have > > to change these checks as well and that sounds like a maint. burden to > > me. > > Would pls. show me some example ? What kind of examples would you like to see. I meant that if the current logic of bacground vs. direct limit changes the code to check it which is at a different place IIRC would have to be kept in sync. That being said, this is my personal opinion, I will not object if there is a general consensus on merging this. I just believe that this is not simply worth adding a single line of code. You can then a lot of harm by setting different values which would pass the added check. -- 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