I have made a little openoffice spreadsheet with the results.
You can have fun entering stuff and seeing the results.
http://peufeu.free.fr/compression.ods
Basically, a laptop having the same processor as my PC and a crummy 15
MB/s drive (like most laptop drives) will get a 2.5x speedup using lzf,
while using 40% CPU for compression and 15% CPU for decompression. I'd say
it's a clear, huuuuge win.
A desktop computer with a modern IDE drive doing 50 MB/s will still get
nice speedups (1.8x on write, 2.5x on read) but of course, more CPU will
be used because of the higher throughput. In this case it is CPU limited
on compression and disk limited on decompression. However soon everyone
will have dual core monsters so...
A big ass RAID will not get much benefit unless :
- the buffer cache stores compressed pages, so compression virtually
doubles the RAM cache
- or the CPU is really fast
- or you put one of these neat FPGA modules in a free Opteron socket and
upload a soft-hardware LZF in it with a few gigabytes/s throughput
...
