-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Chuck,
I knew you'd come through. It's always nice to have a VM hacker around for questions like this. Caldarale, Charles R wrote: >> that they have 2GB/2GB kernel and process memory boundaries > > Windows certainly does have such a boundary (although in certain server > versions, this can be changed to 3GB/1GB user/kernel). Most other OSs > don't have a fixed boundary, but they do have a maximum virtual memory > size (set by ulimit in Linux), and each installation can specify a > default. Hmm.... perhaps I have a virtual memory limit. I have 1GB of physical RAM. While allocating a 3GB heap is pretty stupid for me, I still ought to be able to do it. My ulimit man page sucks. Anyone know how to change the virtual memory limits on Linux 2.6? >> since the Java heap need not be contiguous > > Wouldn't it be nice if that were true. I haven't looked at the Java SE > 6 HotSpot code yet, but in all prior versions of Sun's JVM, the heap was > allocated as one contiguous chunk, including the PermGen. HotSpot has > the ability to shift the boundaries between generations, and thus > requires the heap to be contiguous. Really? That sounds hard to believe. If the heap can grow and shrink, then how can the VM hope to get one bigass memory chunk for the heap? If the heap goes from 512MB to 768MB and the existing heap can't grow that far (in a single heap-top-move operation), does the VM freeze everything and relocate the heap to another section of memory? That doesn't seem right. The fact that the boundaries can be moved really complicates things. I had always assumed that the "heap map" that most people see in pictures was only to make it simpler to understand. I thought that the heaps were located wherever they needed to be. Oh, well. Still, the only remaining reason that 2GB+ wouldn't work is because of a (potential) 2GB contiguous memory allocation restriction. I see no such restriction in the malloc or brk man pages on my system. What gives? - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFF+A4A9CaO5/Lv0PARAtIyAJ97F8a5K+DmfNrstvtEruFdRyXdrwCdEiFa j3AguINPMHBGDwuWSojuTXE= =WK+n -----END PGP SIGNATURE----- --------------------------------------------------------------------- To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
