On Monday, September 24, 2001 10:09:59 PM +0800 Beau Kuiper
> Hi all again,
> I have updated my last set of patches for reiserfs to run on the 2.4.10
> The new set of patches create a new method to do kupdated syncs. On
> filesystems that do no support this new method, the regular write_super
> method is used. Then reiserfs on kupdated super_sync, simply calls the
> flush_old_commits code with immediate mode off.
Ok, I think the patch is missing ;-)
What we need to do now is look more closely at why the performance
increases. There are a few possibilities:
1) larger transactions due to less frequent commits.
2) More efficient metadata writes due to less frequent calls to
3) Less time spent flushing direct->indirect targets due to less frequent
The good news is we can easily separate these. Start by running
debugreiserfs -j /dev/xxx > /tmp/foo
This prints out the transactions still in the log. You are looking for
j_len, which is the length of each transaction. The closer this is to ~900
or so, the more efficient the log is.
Q1) Does your patch increase the average length of the transactions?
Q2) Run the tests again with -o notail (including on pure 2.4.10). Does
the performance gain go down relative to pure 2.4.10?
If Q1 is true, we might be able to tune /proc/sys/vm/bdflush to have
If Q2 is true, we need to tune the way direct->indirect targets get flushed
(this probably neesd to be tuned regardless).
If neither is true, it is probably the less frequent calls to
reiserfs_journal_kupdate, also tunable through the bdflush params.
I'm not saying we don't need your patch, but I'd like to find out for sure
why it is helping.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to firstname.lastname@example.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Sun Sep 30 2001 - 21:00:23 EST