Allow resource constraints to specify the max committed new space size...

Allow resource constraints to specify the max committed new space size
when using snapshots.

The alignment of new space has to match the alignment in the snapshot,
but the max committed amount of memory does not.

For now, we assume that the default semispace size is always used in a
snapshot.

Committed: http://code.google.com/p/v8/source/detail?r=3106

[Erik Corry, 2009-10-21 11:17:08]

The names chosen for the various variables confuse me.  Apart from that it LGTM.

http://codereview.chromium.org/300036/diff/3001/3005
File src/flag-definitions.h (right):

http://codereview.chromium.org/300036/diff/3001/3005#newcode168
Line 168: "max size of (each semispace in) the new generation")
The (each semispace in) text looks outdated to me.

http://codereview.chromium.org/300036/diff/3001/3007
File src/heap.h (right):

http://codereview.chromium.org/300036/diff/3001/3007#newcode254
Line 254: return 2 * young_generation_size_ + old_generation_size_;
I think it makes more sense to return the max physical capacity of the heap than
the max virtual memory address extent of the heap.  So the multiplication by two
and the extra comment should be removed.

http://codereview.chromium.org/300036/diff/3001/3007#newcode891
Line 891: static int snapshot_semispace_size_;
I would prefer these two variables and their associated getters to include the
word 'reserved'.  Also, since snapshot_semispace_size_ is used even when we are
not using snapshots I think it should be called actual_reserved_semispace_size_
and the semispace_size_ variable can then be called
requested_reserved_semispace_size_.

http://codereview.chromium.org/300036/diff/3001/3007#newcode894
Line 894: static int young_generation_size_;
I would prefer this variable and its associated getter to include the syllable
'max'.

http://codereview.chromium.org/300036/diff/3001/3006
File src/spaces.cc (right):

http://codereview.chromium.org/300036/diff/3001/3006#newcode1001
Line 1001: ASSERT(size == 2 * Heap::SnapshotSemiSpaceSize());
Does this assert apply even if we are not running with snapshots?

[Mads Ager (chromium), 2009-10-21 13:26:02]

The variable names in this code is indeed confusing.  I changed the names and I
think it is a bit better now.

Could you have another quick look?

http://codereview.chromium.org/300036/diff/3001/3005
File src/flag-definitions.h (right):

http://codereview.chromium.org/300036/diff/3001/3005#newcode168
Line 168: "max size of (each semispace in) the new generation")
It wasn't, but it is in the latest snapshot. :)

http://codereview.chromium.org/300036/diff/3001/3007
File src/heap.h (right):

http://codereview.chromium.org/300036/diff/3001/3007#newcode254
Line 254: return 2 * young_generation_size_ + old_generation_size_;
This method is only used to setup the virtual memory abstraction so it is
important that this returns the max reserved amount of memory.  Change the name
to MaxReserved.

[Erik Corry, 2009-10-21 13:41:49]

LGTM!

http://codereview.chromium.org/300036/diff/6001/6007
File src/heap.h (right):

http://codereview.chromium.org/300036/diff/6001/6007#newcode252
Line 252: return 4 * reserved_semispace_size_ + max_old_generation_size_;
The 4 here probably deserves a comment.