-XX:+MaximizeHeapSize?

[Florian Weimer]

* Jon Masamitsu:

> Yes, hotspot does do a reserve of a continuous address space for the
> entire heap at initialization with an mmap call using
>
>    MAP_PRIVATE | MAP_NORESERVE | MAP_ANONYMOUS
>
> As the heap is actually expanded the space is mmap'ed with
>
>    MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS
>
> so it can actually be used.  See the reserve_memory() and
> commit_memory() methods
> in os/linux/vm/os_linux.cpp for the details.

This is not sufficient in vm.overcommit_memory = 2 mode.  Without
PROT_NONE, the allocation still counts against the beancounter limit.
Perhaps this is a kernel bug, but is has been this way for quite some
time.