On Fri, Apr 08, 2011 at 11:50:13AM -0700, Joel Becker wrote: > On Thu, Apr 07, 2011 at 10:10:52AM -0700, Sunil Mushran wrote: > > On 04/07/2011 09:40 AM, Darrick J. Wong wrote: > > >That said, I haven't really quantified the performance impact of this naive > > >approach yet, so I wonder -- did you see a similar scenario with ocfs2, and > > >what kind of performance increase did you get by adapting the code to use the > > >jbd2 trigger? If there's potentially a large increase, it would be interesting > > >to apply the same conversion to the group descriptor checksumming code too. > > > > Joel Becker may remember the overhead. He wrote the patch. That said we have few > > differences. ocfs2 has larger (blocksized) inodes. Also, it computes ECC. The code > > is in fs/ocfs2/blockcheck.c. Heh, yes, ext4 uses a fairly simple crc16 and the inodes are (most likely) not block sized. > ocfs2 does the journal access/journal dirty cycle a lot more > than extN. I think you'd want to generate your own numbers. Ok, I ran both the mailserver ffsb profile and a quick-and-dumb test that tried to dirty inodes as fast as it could. On both a regular disk, an SSD, and a loopmounted ext4 on a tmpfs I couldn't really see much of a performance difference at all. I'll see about giving this a try once I get the field location and e2fsck behavior more firmly resolved, though I suspect I won't see much gain. --D -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
