[linux-mm-cc] Advantages of "saving swap space".

[John McCabe-Dansted]

"Swap-out compressed pages as-is. Delay decompression until they are
swapped-in and really used (Purpose here is not to save swap space –
we'll pad out compressed page with 0's when swapping-out)."

Hi, I realise that there are other priorities now, but I'd like to
suggest that there are a number of cases where writing compressed data
to swap space without zero padding would help:

* Video Ram:
  http://hedera.linuxnews.pl/_news/2002/09/03/_long/1445.html

Here, we clearly want to be able to pack as much as possible into the
VRAM swap before having to write to HDD.

* Swap Prefetch:
  http://en.wikipedia.org/wiki/Virtual_memory
The linux Swap Prefetch and the new Windows Vista SuperFetch features
load pages back into memory when you have unused memory. The time
required to do load large amounts of swap back into memory may depend
on the efficiency of the on-disk swap format.  Likewise pre-emptively
writing out swap in contiguous blocks may result in faster
performance.

* USB Swap:
  http://dansdata.com/flashswap.htm