Determining "GC" memory area size

[Aleksey Shipilev]

On 11/10/2017 08:11 PM, Zhengyu Gu wrote:
> 
> 
> On 11/10/2017 01:47 PM, Aleksey Shipilev wrote:
>> On 11/10/2017 06:06 PM, Glyn Normington wrote:
>>> Can anyone here tell me how the GC memory area size is determined? If there
>>> is documentation, so much the better as we'd prefer not to depend on code
>>> details that might flux arbitrarily.
>>
>> NMT reports all allocations from GC code (with mtGC tag) as "GC". This includes, notably, Java heap
>> itself, and all auxiliary GC data structures. If you grep the OpenJDK source for "mtGC", you can get
>> the idea what allocations are tagged. Also, "detailed" NMT mode would give you allocation stacks,
>> which can also give some insight what those particular allocated bits are coming from.
> 
> Java heap actually is *not* tagged as GC memory, but Java heap.

Right. Sorry for the confusion.

-Aleksey