Re: free reporting wrong values?

Robert M. Riches Jr. wrote:
The JVM imposes limits of its own. Try

java -X

to see some of them. The initial and maximum heap sizes are
probably what you're looking for.

The problem with java was that I gave the JVM 2048M initial heap size (-Xmx2048m) which should have been possible according to "free", but the JVM did not even start and instead gave me error messages:

Error occurred during initialization of VM
Could not reserve enough space for object heap
Could not create the Java virtual machine.

So I asked myself (and also the newsgroup) why java was unable to reserve the requested memory although "free" reported that enough was available.

To answer this question I wrote that little C program and found out that it also could not reserve as much memory as "free" reported. Thus, the question is NOT java specific, but more general: Why does "free" report 2.5G of free memory, but only 1.5G are available to an application? (That's exactly what I asked in my original post. Maybe the java stuff was misleading. I just tried to give some context.)

Regards,
Christian
.

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