On Mon, Jun 06, 2011 at 01:12:51PM -0700, Wendy Cheng wrote: > You'll probably get better answer(s) from ext3 user mailing list > .... it is more about how journaling works for the specific file > system. Yes, though leave linux-nfs on the cc: as I'd be interested what you find out. > In ext3 case, I believe "sync" forces data getting flushed to the file > system *regardless* which journal mode is chosen. Using an external > journal device, particularly on SSD, does help but the performance > gain is limited by the amount of data that needs to be written into > the file system itself. > > /etc/exports: > > /plain     Â*(rw,async,no_subtree_check,no_root_squash) > > /split     Â*(rw,async,no_subtree_check,no_root_squash) # (FS with external Journal) > > > > Client mounts were done simply with -o 'rw,rsize=32768,wsize=32768' > > > > Benchmark results: > > Plain Ext3, data=ordered export=sync, write speed 56-62MB/sec > > Split Ext3, data=journal export=sync, write speed = 46-50MB/sec > > > > For reference: > > Plain Ext3, data=ordered export=async, write speed 111MB/sec > > Split Ext3, data=journal export=async, write speed 110MB/sec What exactly is your test? For sufficiently large sequential writes, I wouldn't actually have expected sync vs. async to make much difference: eventually you're limited by the drive speed (I'm assuming your drive does ~60MB/s write througput?). And individual writes (for NFS v3 and higher) aren't necessarily required to be synchronous. A better test would be creating or destroying a bunch of small files, as create and unlink are synchronous (the nfs server won't return, in the sync case, before each create and unlink actually hits the disk). --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
