Re: Ext2 directory index: ALS paper and benchmarks

Hans Reiser (reiser@namesys.com)
Thu, 06 Dec 2001 06:41:17 +0300


I can't comment on your benchmarks because I was on the way to bed when
I read this. I am sure though that you and Stephen are doing your usual
good programming.

ReiserFS is an Htree by your definition in your paper, yes?

Daniel Phillips wrote:

>
>Curiously, Reiserfs actually depends on the spelling of the filename for a
>lot of its good performance. Creating files with names that don't follow a
>lexigraphically contiguous sequence produces far different results:
>
> http://people.nl.linux.org/~phillips/htree/indexed.vs.classic.vs.reiser.10x10000.create.random.jpg
>
>So it seems that for realistic cases, ext2+htree outperforms reiserfs quite
>dramatically. (Are you reading, Hans? Fighting words... ;-)
>

Have you ever seen an application that creates millions of files create
them in random order? Almost always there is some non-randomness in the
order, and our newer hash functions are pretty good at preserving it.
Applications that create millions of files are usually willing to play
nice for an order of magnitude performance gain also.....

I have shared your kpresenter troubles:-)....

Hans

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