Slower performance with ext4

[Mark Kirkwood]

Raphael wrote:
>
>
> Help, after I had clean installed Karmic on my ext4 partition, the 
> performance was significantly slower compared to ext3. Startup was 
> around 7 secs but with ext4 it's now 20 secs application speeds are 
> also slower. 
>

You will get similar performance to ext3 if you disable write barrier 
support (barrier=0 in fstab) see:

http://kernelnewbies.org/Ext4#head-25c0a1275a571f7332fa196d4437c38e79f39f63

However, the write barrier support is a safety feature. However my work 
machine uses ext4 with barriers disabled, so far without any issues.

This got me wondering about barrier support in ext3 - is it not 
implemented or just off by default? From my brief glance at ext3 code, 
there appears to be some stuff about barriers in there, but I couldn't 
see anything about the defaults (you can specify barrier=0/1 for an ext3 
filesystem when mounting - not sure if it has any effect tho!

Regards

Mark