Expose more detailed memory statistics

Expose more detailed memory statistics

Expose allocated and used byte counters for the different spaces. The goal is
to monitor those values both on page cycles and via UMA

BUG=v8:2201
TEST=none

Committed: https://code.google.com/p/v8/source/detail?r=11931

[jochen (gone - plz use gerrit), 2012-06-25 14:49:20]

plz review

[Michael Starzinger, 2012-06-25 15:49:19]

Some general observations:

1) This CL gives you snapshots of the live-bytes (i.e. foo_bytes_used) at points
when a space is expanded. However it doesn't do the same when the space is
shrunk. I think this behavior is counter-intuitive. It might even lead to
situations where it appears there are more live-bytes than allocated memory.

2) Since this provides snapshots of the live-bytes counter, it makes it look
like the live-bytes make huge jumps, although it actually grows steadily over
time. So if you sample with a high sampling rate over these counters, it might
paint misleading picture.

3) Maybe the best solution is to update all of the counters only at GC points.
This would decrease the granularity but make the overall behavior more
intuitive. WDYT?

https://chromiumcodereview.appspot.com/10657022/diff/1/src/spaces.cc
File src/spaces.cc (right):

https://chromiumcodereview.appspot.com/10657022/diff/1/src/spaces.cc#newcode559
src/spaces.cc:559: ObjectSpace space = static_cast<ObjectSpace>(1 <<
owner->identity());
The deoptimizer (i.e. Deoptimizer::CreateCode) uses this allocation method
without providing a valid owner.

[jochen (gone - plz use gerrit), 2012-06-26 09:30:55]

addressed comments

[Michael Starzinger, 2012-06-26 11:36:30]

LGTM.