Hi!
On Mon, 15 Sep 2008 11:54:27 +0200, Pavel Machek wrote:
> Hi!
>
> > +NILFS2 is a log-structured file system (LFS) supporting continuous
> > +snapshotting. In addition to versioning capability of the entire file
> > +system, users can even restore files mistakenly overwritten or
>
> Hmm, undelete done right. Just one question... how slow/fast is it
> compared to conventional filesystems (ext3?)?
> Pavel
After my first submission, Szabolcs Szakacsits showed benchmark
results using compilebench.
On Thu, 21 Aug 2008 00:25:55 +0300 (MET DST)
Szabolcs Szakacsits <szaka@xxxxxxxxxxx> wrote:
> I ran compilebench on kernel 2.6.26 with freshly formatted volumes.
> The behavior of NILFS2 was interesting.
>
> Its peformance rapidly degrades to the lowest ever measured level
> (< 1 MB/s) but after a while it recovers and gives consistent numbers.
> However it's still very far from the current unstable btrfs performance.
> The results are reproducible.
>
> MB/s Runtime (s)
> ----- -----------
> btrfs unstable 17.09 572
> ext3 13.24 877
> btrfs 0.16 12.33 793
> nilfs2 2nd+ runs 11.29 674
> ntfs-3g 8.55 865
> reiserfs 8.38 966
> nilfs2 1st run 4.95 3800
> xfs 1.88 3901
Accordint to his measurement, NILFS2 showed a very low performance
on the first measument, and it recovered after a while.
I still don't know the reason why NILFS2 shows such behaviour, and
I'm thinking to follow the benchmark.
A little while ago, I tried another benchmark on the kernel 2.6.27-rc6.
The iozone benchmark. The result was as follows:
Throughput in MB/s (buffer size = 8B, file size = 500MB)
<write> <rewrite> <read> <reread> <rand-read> <rand-write>
ext3 44.918 46.691 56.541 56.505 1.562 5.716
nilfs2 56.076 43.703 41.364 41.356 1.231 37.650
Throughput in MB/s (buffer size = 64KB, file size = 500MB)
<write> <rewrite> <read> <reread> <rand-read> <rand-write>
ext3 45.369 46.438 56.542 56.457 11.025 36.300
nilfs2 56.119 43.630 41.330 41.498 8.572 37.671
(Here I used -e and -U option to measure true disk read performance
not cache read performance)
As often said for LFS, NILFS2 showed high random write performance
for small writes, but the read throughput was lower. It was about
-27% lower than ext3.
For sequential write, first write was good, but overwrite was slower
because it involves read of existing meta data.
Cheers,
Ryusuke
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