Recommended max. limit of number of files per directory?

[Christian Kujau]

On Wed, 25 Mar 2009, howard chen wrote:
>> If you turn on directory hashing it scales better but eventually
>> performance will still tank. You can use tune2fs to see how it is set and
>> change it if necessay.
> 
> Yes, but I want to know if any testings was performed before?

This made me curious as well, but apart from an rather old benchmark[0] I 
found nothing recent. I wrote a small benchmark script that will touch, 
cat, rm a large amount of files in/from a single directory. The script is 
currently still running, trying to create 10M files on a 4GB partition; 
the results so far:

http://nerdbynature.de/bench/sid/2009-03-26/di-b.log.txt
http://nerdbynature.de/bench/sid/2009-03-26/ 
(dmesg, .config, JFS oops, benchmark script)

However, the correct answer is of course: do these tests with your 
applicaton and see if these results really match. And publish your 
results :)

Christian.

[0] http://lwn.net/Articles/14631/
-- 
Bruce Schneier found the inverse of the constant zero function.