ext3 filesystem performance issues

[Matthew Flaschen]

Bruno Wolff III wrote:
> On Wed, Sep 12, 2007 at 16:25:09 -0400,
>   Matthew Flaschen <matthew.flaschen at gatech.edu> wrote:
>> aragonx at dcsnow.com wrote:
>>> I was told by a coworker that all UNIX varieties have to do an ordered
>>> list search when they have to preform any operations on a directory.  They
>>> also stated that if there is more than 100k files in a directory, these
>>> tools would fail.
>> I'll take that as a challenge.
> 
> I have directories with several million files in them.

Just curious...what for?

> Lookups of a single file seem to be fast,

In a folder with files numbered one through 1 to 200000 (OP said ~100k
was a wall), I get:

time ls -l | wc -l
200004
ls --color=auto -l  1.90s user 0.83s system 98% cpu 2.775 total
wc -l  0.02s user 0.07s system 3% cpu 2.772 total

time touch 30079
touch 30079  0.00s user 0.00s system 13% cpu 0.022 total

These both seem acceptable

> however I have found mv and cp are unexpectedly slow and use up lots of memory. So I expect there are some problems with the way
> that code was written.

Possibly, but most code like this doesn't have problems per se, but
tradeoffs.

Matt Flaschen