Subject: Re: "too many files" in an FFS dir?
To: Paul A Vixie <vixie@mfnx.net>
From: David Brownlee <abs@netbsd.org>
List: tech-kern
Date: 12/18/2000 18:03:05
	I'd be happy to run it on a couple of NetBSD boxes here.

		David/absolute		-- www.netbsd.org: No hype required --


On Sat, 16 Dec 2000, Paul A Vixie wrote:

> > Is there any good reason why I should not plan to store all of the
> > [tens of thousands of] files in one directory?
>
> used to be, yes.  at this point it's merely an urban legend.
>
> > What I know about berkeley ffs suggests not, but it worries me that
> > squid (the http proxy) goes to a great deal of trouble to store small
> > (less than 1000 entries) numbers of cached documents in one directory.
>
> squid has to work well on systems without softdep.  since MAPS and most
> other "ticket systems" need to store a large number of arbitrary-sized
> text objects and then access them randomly, i did some measurements.
>
> http://www.vix.com/~vixie/fbsd-flat.png shows a freebsd 4.2 system putting
> ~75K files (the MAPS RSS if you must know) into a single directory and
> then accessing them in a different order (to prevent implicit double
> buffering).
>
> http://www.vix.com/~vixie/bsdi-flat.png is exactly the same test run on a
> bsd/os 3.1 system.  as you can see, there's a remarkable mode difference.
>
> the difference comes down to soft dependencies.  if someone would like to
> run these tests on netbsd, i'll make my test tools available.
>