read-only compressed fs (call for testers)

Poul-Henning Kamp phk at
Mon Jan 19 11:54:25 PST 2004

In message <20040119182955.GA60760 at>, Max Khon writes:
>I have seen some requests for read-only compressed fs support recently.
>Last weekend I had a few spare cycles and implemented GEOM class that
>allows to use cloop V2.0 (compressed loopback device for Linux) fs images.
>More details, tarballs with geom_ugz and a port for tools needed
>to create/extract compressed fs images are available at

I quickly glanced at this: The one thing which stuck in my mind is
that for performance reasons running inflate in the "up" geom path
may be wrong.

Doing CPU intensive stuff in the "up" and "down" paths is generally
a bad idea and should be avoided because it will hold up other
disk-trafic while the CPU chews.  In GBDE I stuck all the crypto
off to a kthread for this reason.

In this case it may be a valid trade-off, I can't tell, just keep
it in mind down the road.


Have I told anyone how positively delighted I am to see
people grow GEOM classes all the places ?

Wheeeeeeee! :->


Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at 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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