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  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Date:	Fri, 21 Jan 2011 00:13:02 +0000
From:	Jon Leighton <>
Subject: Severe slowdown caused by jbd2 process

Hi there,

I have been experiencing some slowness with an ext4 filesystem. I will
try to explain and hopefully somebody can identify whether this is
"normal" or not. Sorry if I am in any sense unscientific - filesystems
are somewhere near the edge of my computer science knowledge :)

Basically I am involved with doing some development on the Ruby on Rails
web app framework, and the automated tests for one component (Active
Record) does a lot of reading/writing from a database.

I realised that the test suite was running significantly slower for me
than for another developer, so I started to investigate. First I created
an unencrypted partition and put my databases on it, as I had previously
had everything encrypted.

This made it somewhat faster, but not massively.

I then used iotop to see what was going on when I ran the tests. I
discovered that the process jbd2/sda3-8 was doing *lots* of IO when I
run these tests.

I did some googling and tried a few things. Removing the journal solved
the problem (as would be expected, I guess), but also recreating the
partition as ext3 rather than ext4 solved it too (which perhaps
indicates a regression?) When I say 'solved', I mean it took a single
run of this particular test suite from say 4.5 minutes to more like
60-80 seconds.

I found some other people reporting a similar problem:

They complain of the jbd2 process running every few seconds. This is
something I had not noticed before, but I can observe this on my system
too. It runs and uses a lot of IO for a short period of time maybe every
2 seconds. So I think I am experiencing the same problem.

FWIW, using the noatime option does not help at all. Also, I have tried
using a very recent kernel build with no success. And I have run iotop
on another laptop (which also has an ext4 partition) and I cannot
observe this frequent running of jbd2.

So: does this sound like a bug, and if so, what can be done? I'm very
happy to provide any additional information as needed.

Many thanks,


Download attachment "signature.asc" of type "application/pgp-signature" (491 bytes)

Powered by blists - more mailing lists