Leon Rosenberg wrote:
Debian 3.1, kernel 2.6.x-smp (32 bit)
or
Debian 3.1, kernel 2.6.x-smp-emt64 (64 bit)
Hardware: AMD Opteron and Xeon64 (both 64 bit)
SUN jdk1.5 and/or jdk1.4.2
4 GB total RAM for 32-bit linux, with 3/1 memory partitioning
16GB total RAM for 64-bit linux.
I've tested 32/64 bit JVMs extensively and done considerable amount of
JAVA_OPTS tuning for my company's application. On a 32-bit machine you
can't reliably go above a -Xms=1600m without getting OOM errors. With a
3/1 split your virtual page table size for the entire JVM process must
be below 3GB total virtual memory. That's 3GB allocated, not commited.
The JVM allocates a lot more memory besides the heap.
With the 64-bit JVMs, the sky's the limit, however the 64-bit address
also make your application take up more space relative to a 32-bit JVM.
A 3.2GB 64-bit heap space isn't going to double the amount of identical
objects you can create as compared to a 32-bit 1.6GB heap space because
all pointer references will occupy twice the space.
-ryan
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