Journaling UFS with gjournal.

[Pawel Jakub Dawidek]

On Tue, Jun 20, 2006 at 03:20:49PM -0400, Mike Jakubik wrote:
+> Pawel Jakub Dawidek wrote:
+> >Copying one large file:
+> >UFS:		8s
+> >UFS+SU:		8s
+> >gjournal(1):	16s
+> >gjournal(2):	14s
+> >
+> >Copying eight large files in parallel:
+> >UFS:		120s
+> >UFS+SU:		120s
+> >gjournal(1):	184s
+> >gjournal(2):	165s
+> >
+> >Untaring eight src.tgz in parallel:
+> >UFS:		791s
+> >UFS+SU:		650s
+> >gjournal(1):	333s
+> >gjournal(2):	309s
+> >
+> >Reading. grep -r on two src/ directories in parallel:
+> >UFS:		84s
+> >UFS+SU:		138s
+> >gjournal(1):	102s
+> >gjournal(2):	89s
+> >  
+> 
+> Not to sound ungrateful for the work, which i am, this is great! But the performance impact seems rather large to me. Does the presence of journaling mean that we could 
+> perhaps mount the filesystems async? Does it eliminate the need for softupdates?

The performance impact is big for large files, because in theory we have
to write the data twice.
Yes, it eliminates need for SU, but there are reasons, that you still
want to use SU, eg. for snapshots.

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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