Re: benchmarking ext3 in Linux 2.6.0 ?
In the last episode (Dec 18), Michael Elkins said:
> According to this /. post http://tinyurl.com/2ruw5
> >EXT3:
> ># The ext3 filesystem has gained indexed directory support, which
> ># offers considerable performance gains when used on filesystems
> ># with directories containing large numbers of files. In order to
> ># use the htree feature, you need at least version 1.32 of
> ># e2fsprogs. Existing filesystems can be converted using the command
> >tune2fs -O dir_index /dev/hdXXX
> ># The latest e2fsprogs can be found at
> ># http://prdownloads.sourceforge.net/e2fsprogs
>
> This might be interesting for those of you with very large Maildir
> folders.
>
> What other filesystems have good support for accessing files in large
> directories?
FreeBSD had had in-memory directory hashing for ~2 years, enabled by
the UFS_DIRHASH flag. The on-disk layout is unchanged, but as the
kernel accesses large directories, they get hashed for later lookups.
http://www.cnri.dit.ie/Downloads/fsopt.pdf , figure 10 has some
benchmark results. It looks like for MH folders, dirhash gives you a
10x speed increase.
--
Dan Nelson
dnelson@xxxxxxxxxxxxxxx