Re: free reporting wrong values?

At Wed, 11 Jun 2008 08:03:03 +0200 =?ISO-8859-1?Q?Christian_Schr=F6der?= <chschroe@xxxxxxxxxxxxxxxxxxxxxx> wrote:


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

Are you running a 686 (32-bit x86) kernel on a x86_64 machine? Or
32-bit applications on a 64-bit machine?



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