linux-kernel - Re: getdents - ext4 vs btrfs performance

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20120309143446.GO29510@shiny>
Date:	Fri, 9 Mar 2012 09:34:46 -0500
From:	Chris Mason <chris.mason@...cle.com>
To:	Lukas Czerner <lczerner@...hat.com>
Cc:	Jacek Luczak <difrost.kernel@...il.com>,
	linux-ext4@...r.kernel.org,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>, linux-btrfs@...r.kernel.org
Subject: Re: getdents - ext4 vs btrfs performance

On Fri, Mar 09, 2012 at 12:29:29PM +0100, Lukas Czerner wrote:
> Hi,
> 
> I have created a simple script which creates a bunch of files with
> random names in the directory and then performs operation like list,
> tar, find, copy and remove. I have run it for ext4, xfs and btrfs with
> the 4k size files. And the result is that ext4 pretty much dominates the
> create times, tar times and find times. However copy times is a whole
> different story unfortunately - is sucks badly.
> 
> Once we cross the mark of 320000 files in the directory (on my system) the
> ext4 is becoming significantly worse in copy times. And that is where
> the hash tree order in the directory entry really hit in.
> 
> Here is a simple graph:
> 
> http://people.redhat.com/lczerner/files/copy_benchmark.pdf
> 
> Here is a data where you can play with it:
> 
> https://www.google.com/fusiontables/DataSource?snapid=S425803zyTE
> 
> and here is the txt file for convenience:
> 
> http://people.redhat.com/lczerner/files/copy_data.txt
> 
> I have also run the correlation.py from Phillip Susi on directory with
> 100000 4k files and indeed the name to block correlation in ext4 is pretty
> much random :)
> 
> _ext4_
> Name to inode correlation: 0.50002499975
> Name to block correlation: 0.50002499975
> Inode to block correlation: 0.9999900001
> 
> _xfs_
> Name to inode correlation: 0.969660303397
> Name to block correlation: 0.969660303397
> Inode to block correlation: 1.0
> 
> 
> So there definitely is a huge space for improvements in ext4.

Thanks Lukas, this is great data.  There is definitely room for btrfs to
speed up in the other phases as well.

-chris
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/