Ext3 users - Feb 2002 - when does journal flush with data=journal

I'm trying to eek every last bit of performance out of a sync NFS server 
using ext3.

I created a 400MB journal, for my data=journal disk.  When copying a 
200MB file to the machine, by the sound of the disk, it flushed data to 
disk about 4 times, so, about every 50MB.

For the purposes of user experience, it would be great if this could be 
tuned.  I'd set it to just over a couple sigmas out from the average of 
my users' file sizes (lots of big medical imaging slugs).

Is this possible?  Are there defaults?

Thanks,
-Bill

On Feb 08, 2002  12:42 -0500, Bill McGonigle wrote:
> I'm trying to eek every last bit of performance out of a sync NFS
server
> using ext3.
> 
> I created a 400MB journal, for my data=journal disk.  When copying a 
> 200MB file to the machine, by the sound of the disk, it flushed data to 
> disk about 4 times, so, about every 50MB.
I think there is also a 5 second flush interval. IIRC, there is a
parameter which can be tuned, but I don't know the exact mechanism
(compile time, mount option, /proc entry).

Hmm, looking further, it seems it is a compile-time option in
fs/jbd/journal.c:journal_init_common.c where it sets the 
journal_commit_interval.

I thought Andrew at least had a patch to make the journal_commit_interval
match the flush interval for bdflush.

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://www-mddsp.enel.ucalgary.ca/People/adilger/