[Gllug] Reiserfs faster boot

[Nix]

> I copied 100Mb files to /dev/null from both partitions. Both partitions performed identically.

That's a good test --- not. reiserfs's advantage is not in big file
access; that's pretty much always a sheer bandwidth issue with modern
FSen. Its speed avantage is in directory lookup; storage of loads of
files in directories. It's rather slower than ext2fs at extending files
and at creating new ones, and it's *much* slower at hole creation (but
this may not be an issue for you. Oh, and it has considerably higher CPU
overhead than ext2fs).

> There seems much less disk activity with ReiserFS, and programs load faster. 

I doubt *that*'s detectable (mmap()ing a couple of files is
near-instantaneous ext2fs as well); probably they initialize after
loading faster, if they must open/create/manipulat many files at startup
time. (But, of course, that's application-dependent, and varies if you
run the app twice because stuff will already be cached. XEmacs is an
extreme example...)

> It takes 60 seconds to boot to the Gnome desktop with reiser, as
> opposed to 70 with ext2. (taken from pressing enter at the LILO
> prompt).

GNOME is a huge system with many, many variables, so it's hard to say
what's happening here.

> The ext2 partition is 0.7% fragmented. Few of the start-up files are likely fragmented.

Agreed --- although that figure is nearly meaningless for ext2fs anyway
(given that large files (approximately > 2 block groups in size) are
*always* fragmented... the figure you want is an estimate of the ratio
of the number of seeks the disk will have to perform to the number it
would have to perform with an ideally laid out disk, and *that* number
is very hard to work out.

> ReiserFS obviously caches the location of data on the filesystem
> better than ext2.

I don't know what *that*'s supposed to mean; after booting, 

>  Much less time is wasted seeking. 

Seeking is not ext2fs's problem; management of large directories is, and
that's shown by sheer sloth manipulating such (as you'll know if you've
ever `ls'ed a news spool on ext2).

> ReiserFS takes 15% off boot time. 

... in one particular special case (and it's a fairly useless metric
anyway).

> Much less disk seeking in normal use

... for some (unquantified) value of `normal use'.

> find works much faster on the reiser partition.

If you're using 2.4, mkfs your ext2fs filesystems again, make sure
you're using a recent find, and you'll find *they're* faster; the d_type
is stored in the direntry now, cutting out the need to stat every file
to determine if it's a directory or not.

> ReiserFS is worth migrating to!

I still don't quite trust the development team's attitude to
security. They verify that algorithms work in the general case and
assume that means they're robust under malicious attack; unfortunately,
this is not always true :(

-- 
`A truly dreadful film destined to be a cult classic for masochists.'
                                              --- Chris Priest on _A.I._.

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