Also, I'm puzzled why it would the space increase would proportional
to the amount of data and be more than 300 bytes. There's no reason it
wouldn't be a small fixed amount. The ideal is you set aside one bit
-- if the bit is set the rest is compressed and has to save at least
one bit. If the bit is not set then the rest is uncompressed. Maximum
bloat is 1-bit. In real systems it's more likely to be a byte or a
word.
I'm working on cleaning the patch...
I added a field in PageHeader which contains :
- 0 to indicate a non-compressed page
- length of compressed data if compressed
If compression gains nothing (ie gains less than 4K), the page is stored
raw.
It seems that only pages having a PageHeader are handled by md.c, so it
should work (am I mistaken ?)
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