Date: Sat, 29 Nov 1997 05:56:17 +1100 From: Bruce Evans <bde@zeta.org.au> To: bde@zeta.org.au, tlambert@primenet.com Cc: fs@FreeBSD.ORG Subject: Re: ufs slowness Message-ID: <199711281856.FAA10339@godzilla.zeta.org.au>
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I wrote:
>ffs wants to seek a lot to switch cylinder groups (for almost every new
>directory?), but I think the main problem is that it wants to seek lot
>to handle fragments. I'm now making space to repartition. I'll try a
>4K/4K ffs to match the ext2fs block size exactly.
This was the problem. The 4K/4K ffs was about the same speed as a
4K/4K ext2fs, and a 4K/512 ffs was about as slow as an 8K/1K ffs
(20+ seconds vs 40+ seconds). Some analysis of the i/o:
ffs-4K-4K ffs-4K-512
contiguous blocks 7093 3481
forward seeks 450 2857
backwards seeks 258 1647
forward seeks > 64K 407 1037
backward seeks > 64K 211 797
average block size 7013 6055
The drive has an average access time 10.5 ms.
Bruce
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