2.5 ext3 + htree (was: IDE/ATAPI in 2.5)

[Matthias Andree]

On Sun, 14 Jul 2002, Andrew Morton wrote:

> > It wasted 2900 seconds of CPU time on Linux. Let me guess: this was done
> > inside the function strcmp().
> 
> Nope. ext3 and ext2 directories use the traditional first-fit
> search-from-start for directories.  So adding 200k files to
> a single directory is pathological.
> 
> > There are ~ 5 different filesystems on Linux, but none if the projects seem
> > to care about the code outside the FS low level code. I suspect, that
> > this is not any better if you use reiserfs.
> > 
> > Solaris and FreeBSD put all the effort into one filesystem trying to make
> > it as good as possible. In Linux, it seems that nobody prooved the overall
> > concept of the kernel.
> 
> Apply http://www.zip.com.au/~akpm/linux/patches/2.5/2.5.25/ext3-htree.patch
> to your 2.5.25 tree, mount with `-o index' and enjoy watching ext3 eat
> Solaris and FreeBSD's lunch.

I didn't benchmark, but how much lunch is left? UFS_DIRHASH was
introduced into FreeBSD by Ian Dowse a year ago (released in FreeBSD
4.4), and activated in FreeBSD 4.5's generic table. In case you missed
that, FreeBSD 4.6 is out since about four weeks.

options         UFS_DIRHASH             #Improve performance on big directories

http://www.freebsd.org/releases/4.4R/relnotes-i386.html#AEN197
http://www.freebsd.org/releases/4.5R/relnotes-i386.html#AEN250
http://www.cnri.dit.ie/Downloads/Malone_2001_bsdcon.pdf

The latter document by David Malone (November 2001) claims "MH 33 k
files create: 70s to 2.5s, pack: 240s to 2.5s, rm: 4.7s to 2s."

So might be ext3fs comes just in time for dessert, or is htree so much
faster than UFS_DIRHASH?

-- 
Matthias Andree