Comment #14 on issue 2191 by [email protected]: V8 reports heap memory size
bigger than process private memory
http://code.google.com/p/v8/issues/detail?id=2191
"If you are interested in memory consumption you should look at used bytes
(confusingly called "live" in the column) not heap size."
Unfortunately this is not enough for our purposes. We need to show all the
physical memory committed for V8 heap. And it might be up to 2x higher than
the size of actually allocated heap objects.
"We can even reorder these numbers inside the column to put an emphasis on
the right thing: used matters --- heap size matters less."
Well, it's up to you. Probably you're right.
"And once again: V8 does not report amount of virtual address space it just
reserves. Otherwise it would be _way_ higher. It reports amount of memory
it asked OS to commit. It is true that OS can be lazy in performing actual
commit, but that is something beyond V8's reach and actually is not
important to V8 at all as for V8 purposes this memory looks like
successfully committed and can be used for allocation ."
Although it's not that important for v8 (or even for task manager) you can
show apples and oranges to the user. But this is important for DevTools
because we're trying to show the user both apples and oranges on the same
chart and even subtracting one from another. Which is obviously wrong.
"Would you prefer V8 to workaround OSes lazyness by touching every page
inside the region it commits to make numbers of apples and oranges agree? I
can hardly see any reason in that."
Of course not! Increasing process physical memory consumption for the sake
of numbers match in the task manager is not an option. :-)
As a bottomline it seems that unfortunately Heap::CommittedMemory is not ok
for our purposes. So I'm implementing Heap::CommittedPhysicalMemory
function that we will call from DevTools.
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