Slower performance with ext4
Mark Kirkwood
markir at paradise.net.nz
Sat Oct 31 21:52:42 UTC 2009
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
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