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Date:      Thu, 12 Apr 2001 13:18:37 -0300 (BRST)
From:      Rik van Riel <riel@conectiva.com.br>
To:        Matt Dillon <dillon@earth.backplane.com>
Cc:        David Xu <bsddiy@21cn.com>, freebsd-hackers@FreeBSD.ORG
Subject:   Re: vm balance
Message-ID:  <Pine.LNX.4.21.0104121316190.18260-100000@imladris.rielhome.conectiva>
In-Reply-To: <200104110244.f3B2iHk97869@earth.backplane.com>

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On Tue, 10 Apr 2001, Matt Dillon wrote:

>    It's randomness that will kill performance.  You know the old saying
>    about caches:  They only work if you get cache hits, otherwise
>    they only slow things down.

I wonder ... how does FreeBSD handle negative directory entries?

That is, /bin/sh looks through the PATH to search for some executable
(eg grep) and doesn't find it in the first 3 directories.

The next time the script is started (it might be ran for every file
in a large compile) the next invocation of the script looks for the
file in 3 directories where it isn't present .. again.

Does the vfs cache handle this or does FreeBSD have to go down into
the filesystem code every time?

Rik
--
Virtual memory is like a game you can't win;
However, without VM there's truly nothing to lose...

		http://www.surriel.com/
http://www.conectiva.com/	http://distro.conectiva.com.br/


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