Hi,

Due to personal interest, I've hacked up a small program to generate a 
visual representation of swap area allocation. Results are quite
interesting to me, so I've decided to share them with you.

Test program is memtest's "fillmem" (on a 512/512 mem/swap machine).

kernel is 2.6.11-rc4.

stock_second_stage.png: stock allocator after fillmem's first stage
akpm_first_stage.png: akpm's
stock_first_stage.png: stock allocator after fillmem's second stage
akpm_second_stage.png: akpm's

"Legend": 
White: free
Red: used
Black: past end of area

I wonder about the noticeable periodic white regions on akpm's allocator,
my guess is that its due to "properties" of the hash function. Collisions 
could explain that ? Note there is a matching red region for each white 
region. 

There is no noticeable performance difference between the two allocators 
with the "fillmem" workload on my tests.