[aarch64-port-dev ] Issue with 64K page size for JDK7 on AArch64

[Andrew Haley]

On 07/11/14 10:08, Andrew Dinn wrote:
> Anyone have any comments or arguments in favour or against?

I don't know why the heap size has to be rounded up to be an integer
multiple of the size of the card table.  But there may be logic in the
collectors which assumes it is.

It might be that we can get away with allocating card tables which
aren't a multiple of the page size, but I don't know how much code
might break.  Shouldn't be any, but who knows?

The pages are 64k in order to reduce page table walks for machines
with large memory.  So, it is assumed that there will be plenty of
memory on such systems: that's the whole idea.  If you want small
footprint you will not configure your system with 64k pages.  Keep
that in mind.

The right way to fix this problem is, I suspect, not to round down the
size of a heap but to round it up to the next multiple of 32m, and
thank God we no longer have to deal with the permgen.

Andrew.