From: metin d <metdos@yahoo.com>
To: Jaegeuk Hanse <jaegeuk.hanse@gmail.com>
Cc: Jan Kara <jack@suse.cz>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: Problem in Page Cache Replacement
Date: Fri, 23 Nov 2012 00:08:43 -0800 (PST) [thread overview]
Message-ID: <1353658123.36385.YahooMailNeo@web141101.mail.bf1.yahoo.com> (raw)
In-Reply-To: <50AED854.7080300@gmail.com>
----- Original Message -----
From: Jaegeuk Hanse <jaegeuk.hanse@gmail.com>
To: metin d <metdos@yahoo.com>
Cc: Jan Kara <jack@suse.cz>; "linux-kernel@vger.kernel.org" <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/
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
next prev parent reply other threads:[~2012-11-23 8:08 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-20 17:42 Problem in Page Cache Replacement metin d
2012-11-20 18:25 ` Jan Kara
2012-11-21 8:03 ` metin d
2012-11-21 8:13 ` metin d
2012-11-21 8:34 ` Jaegeuk Hanse
2012-11-21 9:02 ` Fengguang Wu
2012-11-21 9:10 ` Fengguang Wu
2012-11-21 9:42 ` Jaegeuk Hanse
2012-11-21 10:00 ` metin d
[not found] ` <1353491880.11679.YahooMailNeo@web141102.mail.bf1.yahoo.com>
[not found] ` <50ACA634.5000007@gmail.com>
2012-11-21 10:07 ` Metin Döşlü
2012-11-22 15:41 ` Fengguang Wu
2012-11-22 15:53 ` Fengguang Wu
2012-11-23 2:10 ` Jaegeuk Hanse
2012-11-25 20:08 ` Rik van Riel
2012-11-24 15:06 ` Metin Döşlü
2012-11-22 15:26 ` Fengguang Wu
2012-11-23 1:32 ` Jaegeuk Hanse
2012-11-23 2:25 ` Fengguang Wu
2012-11-21 21:34 ` Johannes Weiner
2012-11-21 22:01 ` metin d
2012-11-22 0:48 ` Jaegeuk Hanse
2012-11-22 1:09 ` Johannes Weiner
2012-11-22 9:37 ` metin d
2012-11-22 13:16 ` Jaegeuk Hanse
2012-11-22 16:17 ` Johannes Weiner
2012-11-23 2:14 ` Jaegeuk Hanse
2012-11-23 1:58 ` Jaegeuk Hanse
2012-11-23 8:08 ` metin d [this message]
2012-11-23 8:17 ` Jaegeuk Hanse
2012-11-23 8:25 ` metin d
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1353658123.36385.YahooMailNeo@web141101.mail.bf1.yahoo.com \
--to=metdos@yahoo.com \
--cc=jack@suse.cz \
--cc=jaegeuk.hanse@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).