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Re: Ext3fs performance/kjournald deadlock issue



Edward Moon wrote:
> 
> Hi,
> 
> I've got a Redhat 7.2 system:
> Celeron 400
> 512MB RAM
> 18GB SCSI HD (/boot (ext2fs), / (ext3fs))
> 40GB IDE HD (/ (ext3fs))
> 
> I run a bunch of services on the box (apache + mod_perl, MYSQL, Samba,
> etc) but the system is not under heavy load.
> 
> This system has performance issues reading/writing to the ext3fs
> filesystems. The performance issues cropped up when I installed Redhat
> 7.2. Previously the system ran Redhat 6.2 and didn't have the following
> issues:
> 
> Copying files from the IDE drive to the SCSI drive is very
> slow (over 30 minutes transferring 50MB of data).

That's ext3 to ext3, yes?

Something is certainly grossly wrong.  Have you tried mounting all
partitions as ext2?  That'll tell us if it's a filesystem problem,
or something lower down.

You should run `hdparm -t /dev/hdXX' and `hdparm -t /dev/sdXX' to
verify that the disk is running at the expected raw speed.  I suspect
that they are not.   Possibly the 7.2 IDE driver decided to run
your disk in some very slow PIO mode.   You can experiment with
hdparm parameters to tune this up, but be careful - it's easy to
lock your machine when doing this.

> Additionally, I can't play mp3 files from a samba share on this
> machine without winamp pausing every 5-10 seconds. If I copy the mp3 files
> to the local hard drive or to a samba share on a Redhat 6.2 system
> (running ext2fs), the files will play fine.
> 
> I have noticed that cp/smbd seems to deadlock with kjournald. I haven't
> modifed any of the ext3fs settings.

A complete deadlock?  What is it which indicates that the lockup
is in kjournald?
 
> Can I improve performance by changing the journal settings? I think the
> default is to update the journal every 5 seconds? If I increase that to 60
> seconds would that improve performance?
> 

It won't help.  First thing to check is that the raw disk throughput
is decent.

-





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