On Mon, Oct 18, 2010 at 4:50 PM, David T. Lewis <lewis at mail.msen.com> wrote:

> On Mon, Oct 18, 2010 at 04:29:54PM -0700, Colin Putney wrote:
> > On Mon, Oct 18, 2010 at 4:24 PM, David T. Lewis <lewis at mail.msen.com>
> wrote:
> >
> > > In the forseeable future, object memory sizes of more than one or two
> GB are of no practical use.
> >
> > Why do you say that?
> >
>
> Well, basically the garbage collector has a lot of work to do if
> it's managing a lot of memory. Try making a large image and judge
> for yourself.
>

Yes, but some of us are about to start work on a better GC :)  VW has had
users that have been using > 2Gb heaps for almost a decade.  I should have a
new GC running next year and it'd /better/ work well with > 2Gb heaps.

BTW, tags belong in the least significant bits because a) testing them
involves smaller manifest constants and so smaller code size (*) and b)
aligning objects on larger boundaries can have efficiency benefits (e.g. 64
bit writes to initialize objects) and that has the side-effect of making
more tag bits available.

(*) yes testing the msb is cheap iff oop size == word size, but that's only
1 bit that's cheap to test


best,
Eliot


> Dave
>
>
>
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