Re: Compression figures, anyone?

On Fri, 5 Sep 2008, Greg Price wrote:

Hi.

My semi-facetious remark about ZIP archives got me wondering
about what sort of compression ratios users of compressed
extended-format data sets are getting.

From my reading, SMS uses LZW type compression. I guess that is what ZIP
uses as well.


Zipping text can get 75% to 90% compression (ie. reducing the
data to 25% to 10% of its size). How's that compare?

Of course, no matter what the size reduction is, I'd expect it
to use a lot less CPU time than a zipping app.

How much money are you willing to lose on this? In our testing on a z800
(may be better now), SMS compression was "too expensive" in terms of CPU
to implement in a general case. SMS compression is likely implemented in
millicode, so it will not be __significantly__ faster than an optimal
HLASM implementation LZW, which I assume ZIP has.


So, anyone care to share?

TIA,
Greg P.

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--
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Maranatha!
John McKown

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