Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756832Ab3CFKOP (ORCPT ); Wed, 6 Mar 2013 05:14:15 -0500 Received: from zill.ext.symas.net ([69.43.206.106]:46053 "EHLO zill.ext.symas.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754596Ab3CFKON (ORCPT ); Wed, 6 Mar 2013 05:14:13 -0500 Message-ID: <513716F3.4070100@symas.com> Date: Wed, 06 Mar 2013 02:14:11 -0800 From: Howard Chu User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:22.0) Gecko/20100101 Firefox/22.0 SeaMonkey/2.19a1 MIME-Version: 1.0 To: linux-kernel Subject: Re: mmap vs fs cache References: <5136320E.8030109@symas.com> <513685D6.7080102@symas.com> In-Reply-To: <513685D6.7080102@symas.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1486 Lines: 32 Howard Chu wrote: > Howard Chu wrote: >> 2 questions: >> why is there data in the FS cache that isn't owned by (the mmap of) the >> process that caused it to be paged in in the first place? >> is there a tunable knob to discourage the page cache from stealing from the >> process? > > This Unmapped page cache control http://lwn.net/Articles/436010/ sounds like > it might have been helpful here. I.e., having a way to prioritize so that > unmapped cache pages get reclaimed in preference to mapped pages could help. > Though I still don't understand why these pages in the cache aren't mapped in > the first place. > As implied by this post http://lkml.indiana.edu/hypermail/linux/kernel/0701.3/0354.html setting swappiness to 0 seems to give the desired effect of preventing mapped pages from being reclaimed. If this is an intended effect, it would be nice to have this documented in Documentation/sysctl/vm.txt. If this is not the intended effect, please don't "fix" this without providing a supported means of doing the same. -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/ -- 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/