Improved GC statistics (cumulative and per collection).

Improved GC statistics. 

Collect cumulative (--print-cumulative-gc-stat) and per collection (--trace-gc-nvp) GC statistics and output it in a machine-readable name=value format.

Committed: http://code.google.com/p/v8/source/detail?r=4675

[Mads Ager (chromium), 2010-05-18 08:57:48]

LGTM

http://codereview.chromium.org/2132005/diff/2001/3002
File src/heap.cc (right):

http://codereview.chromium.org/2132005/diff/2001/3002#newcode649
src/heap.cc:649: if (MarkCompactCollector::IsCompacting()) {
Seems like a left-over change since this just unconditionally increments
mc_count_.

http://codereview.chromium.org/2132005/diff/2001/3003
File src/heap.h (right):

http://codereview.chromium.org/2132005/diff/2001/3003#newcode1647
src/heap.h:1647: explicit Scope(GCTracer* tracer, ScopeId scope)
You can remove |explicit| now.

http://codereview.chromium.org/2132005/diff/2001/3003#newcode1740
src/heap.h:1740: int start_holes_;
|start_holes_| doesn't really capture what the comment is saying. How about:
in_free_list_or_wasted_?

[Vyacheslav Egorov (Chromium), 2010-05-18 09:06:32]

http://codereview.chromium.org/2132005/diff/2001/3002
File src/heap.cc (right):

http://codereview.chromium.org/2132005/diff/2001/3002#newcode649
src/heap.cc:649: if (MarkCompactCollector::IsCompacting()) {
On 2010/05/18 08:57:48, Mads Ager wrote:
> Seems like a left-over change since this just unconditionally increments
> mc_count_.

Sorry I am not following you: I think we can have !IsCompacting() here that
means that we are doing MarkSweep collection.

[Mads Ager (chromium), 2010-05-18 09:46:55]

http://codereview.chromium.org/2132005/diff/2001/3002
File src/heap.cc (right):

http://codereview.chromium.org/2132005/diff/2001/3002#newcode649
src/heap.cc:649: if (MarkCompactCollector::IsCompacting()) {
On 2010/05/18 09:06:32, Vyacheslav Egorov wrote:
> On 2010/05/18 08:57:48, Mads Ager wrote:
> > Seems like a left-over change since this just unconditionally increments
> > mc_count_.
> 
> Sorry I am not following you: I think we can have !IsCompacting() here that
> means that we are doing MarkSweep collection. 

My bad. I missed the one char difference between mc_count_ and ms_count_. :)

[Vyacheslav Egorov (Chromium), 2010-05-18 16:35:03]

http://codereview.chromium.org/2132005/diff/2001/3003
File src/heap.h (right):

http://codereview.chromium.org/2132005/diff/2001/3003#newcode1647
src/heap.h:1647: explicit Scope(GCTracer* tracer, ScopeId scope)
On 2010/05/18 08:57:48, Mads Ager wrote:
> You can remove |explicit| now.

Done.

http://codereview.chromium.org/2132005/diff/2001/3003#newcode1740
src/heap.h:1740: int start_holes_;
On 2010/05/18 08:57:48, Mads Ager wrote:
> |start_holes_| doesn't really capture what the comment is saying. How about:
> in_free_list_or_wasted_?

I renamed the field but in fact free list nodes and wasted bytes form exactly
"holes" in old space.