Understanding the -A and the -H flags

[Johan Tibell]

Hi Simon,

On Mon, Feb 27, 2012 at 12:25 AM, Simon Marlow <marlowsd at gmail.com> wrote:
> "Think of -Hsize as a variable -A option. It says: I want to use at least
> size bytes, so use whatever is left over to increase the -A value."
>
> Doesn't that describe exactly what it means?

Maybe. Let me start with the mental model I approach this with: the
allocation area (i.e. the nursery) should have a size in the order of
megabytes, often around the size of the L2 cache.

Given this model, I read the above as:

 * if you set e.g. -H1G, you'll get an allocation area which is in the
order of 1Gb large. That makes no sense to me.
 * The suggested size of the total heap (-H) has something to do with
the size of the allocation area (-A). This makes no sense to me
either.

So either I do understand what -H does, but it makes no sense to me,
or I don't understand what -H does, but what it does makes sense.

Perhaps the confusion lies in the phrase "left over." Left over from what?

Cheers,
  Johan