16Gb Ram and page file

November 7, 2007

I have a new system w/ 16GB of RAM. I'm running a Java application that can

very easily use this much memory. My problem is in how to best use RAM and

page file.

What I'd like to do is allocate 15GB of RAM to the Java virtual machine and

allow the system to use as much memory as possible, no paging. However, if I

set any value for the page file (e.g. 64Gb), the system seems to allow only

around 2Gb of page file to be used (~1Gb physical memory). During program

execution, once this 2GB PF/1GB RAM limit is hit, performance goes WAY

down...haltingly slow.

However, if I turn off the page file altogether and run the application w/

15GB for the JVM, the program runs extremely fast. In fact, peak memory usage

is over 5Gb. Interestingly, the amount of page file allocated immediately

goes to 15GB when the program starts, telling me that the JVM is carving out

15GB of physical RAM for its use. Another thing I noticed, and I may be wrong

here, is that disk I/O seemed to be slow and took up more physical memory

than before.

My question is: should I just turn off the page file use forever? Or is

there a way to get the best of both worlds?

Recommended Posts