Why not run the VM with a fixed amount of heap memory?
EG: -Xms1500m -Xmx1500m [-server] # fix the heap size at 1.5GB 

Advantages are:
(a) Dynamic heap resizing is avoided thereby 
avoiding issues to do with object copies, heap fragmentation, generational gc etc
(b) Garbage collection is avoided as long as possible.

I like to run my VM heap fixed at about 75-85% of primary memory.

I would have thought the IO costs to do with logging, perhaps check-pointing, etc
would have been significant, perhaps even dominant. Discounting, of course fitness evaluation for
"non-trivial" problems. 

Shane Magrath
Doctoral Researcher
University of Technology Sydney
PH: 61 2 9514 2527

UTS CRICOS Provider Code: 00099F
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