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Date:      Wed, 27 Oct 1999 14:51:55 -0700 (PDT)
From:      Julian Elischer <julian@whistle.com>
To:        Mike Smith <mike@smith.net.au>
Cc:        Ilia Chipitsine <ilia@cgilh.chel.su>, David Scheidt <dscheidt@enteract.com>, Chuck Robey <chuckr@picnic.mat.net>, Ben Rosengart <ben@skunk.org>, Chuck Youse <cyouse@paradox.nexuslabs.com>, questions@FreeBSD.ORG, hackers@FreeBSD.ORG
Subject:   Re: why FFS is THAT slower than EXT2 ? 
Message-ID:  <Pine.BSF.4.10.9910271450410.10461-100000@current1.whistle.com>
In-Reply-To: <199910271853.LAA00409@dingo.cdrom.com>

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On Wed, 27 Oct 1999, Mike Smith wrote:

> > in order to save space I gzip'ped output of my tests. 
> > ungzipping ports tarball on FreeBSD took 28 min
> > on Linux --- about 2.5 times faster.
> 
> This is something we already know, and it's not the sort of test that 
> you should ever headline as "why is FFS so much slower"?

Kirk has said that it would be possible for the FFS to modify its
behaviour if it notices this usage pattern.

> 
> Creation of massive directory tree hierarchies under FFS is more
> expensive because of the way that FFS tries to keep directories spread
> out, in order to later have a better chance of putting files close to
> their parent directories.  When you create a massive and mostly empty
> tree like the ports tree, you pay for this optimisation.   The
> justification for this behaviour is that you only create the tree once,
> but you may use it for years afterwards.
> 
> Thus, claiming that "FFS is slower" is both short-sighted and 
> incorrect.  If you're going to bother to publicise the results of your 
> tests, you could try actually conducting some meaningful tests first.
> 
> 
> -- 
> \\ Give a man a fish, and you feed him for a day. \\  Mike Smith
> \\ Tell him he should learn how to fish himself,  \\  msmith@freebsd.org
> \\ and he'll hate you for a lifetime.             \\  msmith@cdrom.com
> 
> 
> 
> 
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