How much -XX:MaxPermSize size i can mention for 4GB and 8GB Ram and calculation for this?

Question

How much -XX:MaxPermSize size i can mention for 4GB and 8GB Ram. Here are the other detalis of my system

OS:-window XP(32 bit) RAM:-4 GB java_opt- -Xms1536m -Xmx1536m //(mentioned as environment variable): tomcat version:-6.0.26

I have another system with 8GB ram with other details exactly same . Yes os is 64 bit Window 7.

Along with this also let me know what can be the max value for -Xmx parameter for both the systems?

It would be great if some body can tell me the calculation to arrive at the figure so that we dont have to cram this figure but we can logically calculate based on RAM ssytem is having?

I have really seen people getting permgen error or heap error but every body keeps on playing with this paramters until they come to figure that resolve the issue.

Answer 1

According to IBM document, application runs with a minimum heap usage of 40%, and a maximum heap usage of 70%.

Refer to this information

Why can't I get a larger heap with the 32-bit JVM?

Max amount of memory per java process in windows?

Sizing the Java heap