CD9660/md(4)/UFS22 silly behaviour

I'm doing som data-mining on a pile of ISO images right now.

I stuck the ISOs on a UFS2 on a flash-disk for speed, and mdconfig(8)'d
them so I could mount them.

The traffic pattern his "interesting":

dT: 1.003s  w: 1.000s
 L(q)  ops/s    r/s   kBps   ms/r    w/s   kBps   ms/w   %busy Name
[...]
    1    733    733   1466    1.3      0      0    0.0   98.2| md39
    1    733    733  23449    1.3      0      0    0.0   93.2| da0

Notice the 1:16 ratio on kBps but 1:1 ratio on ops/s ?

da0's UFS2 has 32k block-size:

	magic   19540119 (UFS2) time    Wed Jan  4 16:41:47 2012
	superblock location     65536   id      [ 4f046cf5 c30697ee ]
	ncg     104     size    19537685        blocks  19228156
	bsize   32768   shift   15      mask    0xffff8000
	fsize   4096    shift   12      mask    0xfffff000
	[...]

It looks like every 2k read from CD9660 turns into a 32k block
read in the UFS filesystem, without any beneficial caching happening.

Less than optimal I'd say...

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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