Messages in this thread | | | Date | Fri, 23 Nov 2012 00:25:15 -0800 (PST) | From | metin d <> | Subject | Re: Problem in Page Cache Replacement |
| |
----- 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" <linux-mm@kvack.org> Sent: Friday, November 23, 2012 10:17 AM Subject: Re: Problem in Page Cache Replacement
On 11/23/2012 04:08 PM, metin d wrote: > ----- 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/
> 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
Hi Jaegeuk,
You may need to install mercurial on your system, I'm able to download source code with this command:
hg clone https://code.google.com/p/linux-ftools/
Regards, Metin
> > > 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 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/
| |