Re: [Ext2-devel] Re: Shrinking ext3 directories

Stephen C. Tweedie
2002-06-19T23:55:07Z

Hi,

On Wed, Jun 19, 2002 at 11:43:40PM +0100, Stephen C. Tweedie wrote:

> Well, it has some interesting properties, such as the hash function
> being a constant:
>
> + return 80; /* FIXME: for test only */
>
> which I assume was an artifact of some testing Christopher was doing.
> :)
>
> I'm checking out a proper hash function at the moment.

Done, checked into ext3 cvs (features-branch again.)

Deleting and recreating 100,000 files with this kernel:

[root@spock test0]# time xargs rm -f < /root/flist.100000

real 0m14.305s
user 0m0.750s
sys 0m5.430s
[root@spock test0]# time xargs touch < /root/flist.100000

real 0m16.244s
user 0m0.530s
sys 0m6.660s

that's an average of 160usec per create, 140usec per delete elapsed
time, and 66/54usec respectively system time.

I assume the elapsed time is greater only because we're starting to
wrap the journal due to the large amount of metadata being touched
(we're touching a lot of inodes doing the above, which I could avoid
by making hard links instead of new files.) Certainly, limiting the
test to 10,000 files lets it run at 100% cpu.

--Stephen