From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx173.postini.com [74.125.245.173]) by kanga.kvack.org (Postfix) with SMTP id 9EB3D6B006C for ; Fri, 23 Nov 2012 03:18:04 -0500 (EST) Received: by mail-da0-f41.google.com with SMTP id e20so2550586dak.14 for ; Fri, 23 Nov 2012 00:18:04 -0800 (PST) Message-ID: <50AF3134.3090803@gmail.com> Date: Fri, 23 Nov 2012 16:17:56 +0800 From: Jaegeuk Hanse MIME-Version: 1.0 Subject: Re: Problem in Page Cache Replacement References: <1353433362.85184.YahooMailNeo@web141101.mail.bf1.yahoo.com> <20121120182500.GH1408@quack.suse.cz> <50AED854.7080300@gmail.com> <1353658123.36385.YahooMailNeo@web141101.mail.bf1.yahoo.com> In-Reply-To: <1353658123.36385.YahooMailNeo@web141101.mail.bf1.yahoo.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: metin d Cc: Jan Kara , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" On 11/23/2012 04:08 PM, metin d wrote: > ----- Original Message ----- > > From: Jaegeuk Hanse > To: metin d > Cc: Jan Kara ; "linux-kernel@vger.kernel.org" ; linux-mm@kvack.org > Sent: Friday, November 23, 2012 3:58 AM > Subject: Re: Problem in Page Cache Replacement > > On 11/21/2012 02:25 AM, Jan Kara wrote: >> On Tue 20-11-12 09:42:42, metin d wrote: >>> I have two PostgreSQL databases named data-1 and data-2 that sit on the >>> same machine. Both databases keep 40 GB of data, and the total memory >>> available on the machine is 68GB. >>> >>> I started data-1 and data-2, and ran several queries to go over all their >>> data. Then, I shut down data-1 and kept issuing queries against data-2. >>> For some reason, the OS still holds on to large parts of data-1's pages >>> in its page cache, and reserves about 35 GB of RAM to data-2's files. As >>> a result, my queries on data-2 keep hitting disk. >>> >>> I'm checking page cache usage with fincore. When I run a table scan query >>> against data-2, I see that data-2's pages get evicted and put back into >>> the cache in a round-robin manner. Nothing happens to data-1's pages, >>> although they haven't been touched for days. >> Hi metin d, >> fincore is a tool or ...? How could I get it? >> Regards, >> Jaegeuk > > Hi Jaegeuk, > > Yes, it is a tool, you get it from here : > http://code.google.com/p/linux-ftools/ Hi Metin, Could you give me a link to download it? I can't get it from the link you give me. Thanks in advance. :-) Regards, Jaegeuk > > > Regards, > Metin >>> Does anybody know why data-1's pages aren't evicted from the page cache? >>> I'm open to all kind of suggestions you think it might relate to problem. >> Curious. Added linux-mm list to CC to catch more attention. If you run >> echo 1 >/proc/sys/vm/drop_caches >> does it evict data-1 pages from memory? >> >>> This is an EC2 m2.4xlarge instance on Amazon with 68 GB of RAM and no >>> swap space. The kernel version is: >>> >>> $ uname -r >>> 3.2.28-45.62.amzn1.x86_64 >>> Edit: >>> >>> and it seems that I use one NUMA instance, if you think that it can a problem. >>> >>> $ numactl --hardware >>> available: 1 nodes (0) >>> node 0 cpus: 0 1 2 3 4 5 6 7 >>> node 0 size: 70007 MB >>> node 0 free: 360 MB >>> node distances: >>> node 0 >>> 0: 10 >> Honza -- 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