Ext3 users - Nov 2003 - performance gain in data journalling mode

hi,

If I understand correctly, full journalling mode gives better 
performance for applications that do a lot of updates in O_SYNC. Could 
you please explain how this is possible? Doesn't full data journalling 
do twice as many writes as meta data journalling?

han

On Nov 22 Wen-han Goh wrote:
>If I understand correctly, full journalling mode gives better 
>performance for applications that do a lot of updates in O_SYNC. Could 
>you please explain how this is possible? Doesn't full data journalling 
>do twice as many writes as meta data journalling?
Yes it does; however, once the data is in the journal the O_SYNC caller 
can continue. With other modes you have to wait until the journal is 
committed, and all the extra seeks that may ensue...

Matt