Re: New Feature Idea: Compress swap file

Peter Moulder (
26 Feb 1998 10:48:29 +1100

Arnd Bergmann <> writes:

> You could even let the fs code do the compression for
> you, when you have your swap space on a e2compr (see
> ).

As I say, it would only work if the swapping code used the mmap
interface of readpage and write, as e2compr doesn't provide a block

If people want to try compressed swapping, have a look at DouBle, by
Jean-Marc Verbavatz. It provides a compressed block device. You tell
it the name of a block device or (fixed-size) regular file, some
compression parameters (compression algorithm, cluster size, storage
granularity), and a (conservative) expected compression ratio. It
then provides a block device (say /dev/dbl0) that has more blocks than
the file or device where the data is actually being stored.

URL for DouBle is <>.
There's also a (old, last time I looked) version on sunsite.

I imagine that the same optimisations apply to that as apply to any
compressed swapping system, so why don't people have a look at that
and make any necessary optimisations to that.

I don't think there's much more point in continuing this thread.


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