Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754877AbZFDIk5 (ORCPT ); Thu, 4 Jun 2009 04:40:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751783AbZFDIku (ORCPT ); Thu, 4 Jun 2009 04:40:50 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:54183 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751650AbZFDIkt (ORCPT ); Thu, 4 Jun 2009 04:40:49 -0400 Date: Thu, 4 Jun 2009 17:39:18 +0900 From: KAMEZAWA Hiroyuki To: balbir@linux.vnet.ibm.com Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "nishimura@mxp.nes.nec.co.jp" Subject: Re: [PATCH] remove memory.limit v.s. memsw.limit comparison. Message-Id: <20090604173918.3b2c68f5.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090604083110.GD7504@balbir.in.ibm.com> References: <20090604141043.9a1064fd.kamezawa.hiroyu@jp.fujitsu.com> <20090604083110.GD7504@balbir.in.ibm.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.5.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2021 Lines: 54 On Thu, 4 Jun 2009 16:31:10 +0800 Balbir Singh wrote: > * KAMEZAWA Hiroyuki [2009-06-04 14:10:43]: > > > From: KAMEZAWA Hiroyuki > > > > Removes memory.limit < memsw.limit at setting limit check completely. > > > > The limitation "memory.limit <= memsw.limit" was added just because > > it seems sane ...if memory.limit > memsw.limit, only memsw.limit works. > > > > But To implement this limitation, we needed to use private mutex and make > > the code a bit complated. > > As Nishimura pointed out, in real world, there are people who only want > > to use memsw.limit. > > > > Then, this patch removes the check. user-land library or middleware can check > > this in userland easily if this really concerns. > > > > And this is a good change to charge-and-reclaim. > > > > Now, memory.limit is always checked before memsw.limit > > and it may do swap-out. But, if memory.limit == memsw.limit, swap-out is > > finally no help and hits memsw.limit again. So, let's allow the condition > > memory.limit > memsw.limit. Then we can skip unnecesary swap-out. > > > > Signed-off-by: KAMEZAWA Hiroyuki > > We can't change behaviour this way without breaking userspace scripts, > API and code. What does it mean for people already using these > features? Does it break their workflow? > Hopefully no breaks to current users's workflow. Because this just has influences to "error path" like below echo 200M > memory.memsw.limit echo 300M > memory.limit => ERROR If the user program made in sane way, above case will never happens because they set memsw.limit to be greater than memory.limit and above is treated as error. Thanks, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/