The patch from Stephen Tweedie allows users to modify the journal
commit interval for the ext3 filesystem.

The commit interval is normally five seconds.  For portable computers
with spun-down drives it is advantageous to be able to increase the
commit interval.

There may also be advantages in decreasing the commit interval for
specialised applications such as heavily-loaded NFS servers which are
using synchronous exports.

The laptop users will also need to increase the pdflush periodic
writeback interval (/proc/sys/vm/dirty_writeback_centisecs), because
the `kupdate' activity also forces a commit.

To specify the commit interval, use

	mount -o commit=30 /dev/hda1 /mnt/whatever

or
	mount -o remount,commit=30 /dev/hda1

The commit interval is specified in units of seconds.