Increase memory limits for IcedTea

Peter B. Kessler Peter.Kessler at Sun.COM
Mon Oct 8 13:56:11 PDT 2007

Andrew Haley wrote:

> Peter B. Kessler writes:
> ....
>  > The right solution is to make it so the heap doesn't have to
>  > be in contiguous memory.  Anyone want to help work on that?
> Hmm.  Surely it's better / more efficient to ask the kernel to map a
> contiguous range of pages rather than for the VM do more work in user
> space.  The nice thing about Java on Linux is that we're in a position
> to ask the kernel engineers to help us with what we need.
> Andrew.

You are probably thinking of reasonable users who want to run in
reasonable heaps that leave plenty of address space for other bits
of the process.  We get the phone calls from the folks that want
to shoehorn the largest possible heap into their address space.
Contiguous heaps are pain for them.

The problem is that we don't know in advance if they will want the
address space for Java heap, thread stacks, libraries, malloc space,
etc.  Otherwise we'd just reserve the whole address space for the
heap.  That wouldn't leave any room for anything else, though.
It would be better to only reserve the space we need, do the work
to make the heap not need contiguous addresses, and make it all work
efficiently in the kernel.  (We talk to the kernel engineers for our
favorite operating system, too. :-)

			... peter

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