Problem with java heap size

General talk
1

A month ago I could start mkgmap, osmosis, splitter, etc. with the command

java -Xmx1600m -jar ...

After a motherboard change of my machine, I re-installed Windows XP professional (32 Bit) and all programs, incl. Java Runtime Environment version 1.6.0_25. The machine has 4 GB RAM, where about 3.5 GB can be used with a 32 Bit operating system. The task manager says that more than 23000 MByte RAM is available with running windows. Additional virtual memory is about 4 GB. Now the maximum possible value for the heap space is significantly reduced, so I can not reserve more than 1100 MByte:

java -Xmx1100m -jar ...

On another (much smaller) machine with only 1 GB RAM, XP home and Java Runtime Environment 1.6.0_22, I can reserve 1400 MByte with no problem.

Has anyone an idea, how I can come back to my old 1600 MByte heap usage?

2

Does this help?
http://stackoverflow.com/questions/2457514/understanding-max-jvm-heap-size-32bit-vs-64bit
http://www.oracle.com/technetwork/java/hotspotfaq-138619.html#gc_heap_32bit

It basically says that the maximum heap size for a 32bit windows machine differs from machine to machine…

3

Not really… Although it was interesting to me that windows uses some space in the middle of free memory, so that only about 1.5 GByte contiguous memory is left.

What I don’t understand is, that I already had 16000 MByte and after reinstallation of windows and programs, I have only 11000 MByte.

The question is, what software setting caused this change. The hardware is still the same.