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Date: Mon, 27 Jan 1997 16:53:51 +1100
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199701270553.QAA25341@godzilla.zeta.org.au>
To: dicen@hooked.net, toor@dyson.iquest.net
Subject: Re: What is the default for async in /etc/fstab?
Cc: freebsd-hackers@freebsd.org
Sender: owner-hackers@freebsd.org
X-Loop: FreeBSD.org
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>> Have other people tested ufs vs. ext2? The only docs I could find where
>> ...
>The performance that I have measured (sequential -- IOZONE) is that
>FreeBSD is faster in both read/write.  However, our metadata performance
>is slower (filecreates/deletes.)  With -async, our metadata is still
>slower, but not by orders of magnitude.  FreeBSD's cache perf is much
>faster (by factors of 3-4.)  Much of it is due to the default block
>size (8K vs. 1K.)  But the fragment size of an 8K UFS filesystem is
>the *same* as a 1K ext2fs.

In my tests, ext2fs is fastest for huge sequential i/o's when the block
sizes are closer (8K vs 4K), but there was only a small difference (less
than 10%) between the best and worst cases (best: ext2fs under FreeBSD,
next: ext2fs under Linux, worst: ext2fs under Linux) except for rewrite,
which was 66% faster under Linux than under FreeBSD.  Cache performance
also catches up (46MB/sec for FreeBSD-current-last-November, 41MB/sec
for Linux-2.0.20).  A 4K fragment size wastes space probably wastes time
in most cases.

Bruce