From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx132.postini.com [74.125.245.132]) by kanga.kvack.org (Postfix) with SMTP id D5D0E6B0002 for ; Thu, 21 Mar 2013 04:59:33 -0400 (EDT) Received: from /spool/local by e28smtp05.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 21 Mar 2013 14:26:47 +0530 Received: from d28relay05.in.ibm.com (d28relay05.in.ibm.com [9.184.220.62]) by d28dlp01.in.ibm.com (Postfix) with ESMTP id CB06EE0053 for ; Thu, 21 Mar 2013 14:30:55 +0530 (IST) Received: from d28av02.in.ibm.com (d28av02.in.ibm.com [9.184.220.64]) by d28relay05.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r2L8xOxm5177850 for ; Thu, 21 Mar 2013 14:29:24 +0530 Received: from d28av02.in.ibm.com (loopback [127.0.0.1]) by d28av02.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r2L8xQYa016900 for ; Thu, 21 Mar 2013 19:59:26 +1100 Date: Thu, 21 Mar 2013 16:59:24 +0800 From: Wanpeng Li Subject: Re: [PATCH] mm: page_alloc: Avoid marking zones full prematurely after zone_reclaim() Message-ID: <20130321085924.GA13665@hacker.(null)> Reply-To: Wanpeng Li References: <20130320181957.GA1878@suse.de> <514A7163.5070700@gmail.com> <20130321081902.GD6094@dhcp22.suse.cz> <514AC583.2090909@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <514AC583.2090909@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Simon Jeons Cc: Michal Hocko , Mel Gorman , Andrew Morton , Hedi Berriche , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu, Mar 21, 2013 at 04:32:03PM +0800, Simon Jeons wrote: >Hi Michal, >On 03/21/2013 04:19 PM, Michal Hocko wrote: >>On Thu 21-03-13 10:33:07, Simon Jeons wrote: >>>Hi Mel, >>>On 03/21/2013 02:19 AM, Mel Gorman wrote: >>>>The following problem was reported against a distribution kernel when >>>>zone_reclaim was enabled but the same problem applies to the mainline >>>>kernel. The reproduction case was as follows >>>> >>>>1. Run numactl -m +0 dd if=largefile of=/dev/null >>>> This allocates a large number of clean pages in node 0 >>>I confuse why this need allocate a large number of clean pages? >>It reads from file and puts pages into the page cache. The pages are not >>modified so they are clean. Output file is /dev/null so no pages are >>written. dd doesn't call fadvise(POSIX_FADV_DONTNEED) on the input file >>by default so pages from the file stay in the page cache > >Thanks for your clarify Michal. >dd will use page cache instead of direct IO? Where can I got dd >source codes? >One offline question, when should use page cache and when should use >direct IO? who prefer direct IO: - the users believe they can manage caching of file contents better than the kernel can. - the users want to avoid overflowing the page cache with data which is unlikely to be of use in the near future. Regards, Wanpeng Li > > >-- >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 -- 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