On Wed, Apr 03, 2002 at 02:23:01PM +0200, Diego SANTA CRUZ wrote: > On Wed, 2002-04-03 at 11:21, Andreas Dilger wrote: > [snip] > > Note that it is possible for the entire > > journal to be pinned in memory, so if you make the journal too large, > > you may have memory problems. > > > > Interesting point! > > How is this affected if there are several ext3 filesystems mounted? Can > all journals be resident in memory at a time? > > I have 5 ext3 filesystems, 4 of them with a 32MB journal, and one with a > 1MB journal (small /boot partition). Does this mean that I can have 129 > MB of memory used by the ext3 journals? Yes. If your system is IO stressed and the VM doesn't think you need that memory for other purposes. > Since this is a laptop (256 MB) and normally there is not that much fs > activity (although sometimes I do really stress it), is it advisable to > reduce the journal size to avoid the above problem (if it is a problem > that is)? Not really. When the journal gets about 50% full, it will force everything else to wait while it finishes emptying the journal. With writeback, and ordered mode that would be a hard task to fill the journal up to 50%, but with data=journal mode it is quite easy. Mike
