RFR(XXS) 8187629: NMT: Memory miscounting in compiler (C2)

[Vladimir Kozlov]

On 9/19/17 10:19 AM, Zhengyu Gu wrote:
> Hi Vladimir,
> 
> I filed a bug to track this issue.
> 
> https://bugs.openjdk.java.net/browse/JDK-8187685

Yes, lets do it separately.
Your current fix is good.

Thanks,
Vladimir

> 
> Thanks,
> 
> -Zhengyu
> 
> On 09/19/2017 12:52 PM, Vladimir Kozlov wrote:
>> On 9/19/17 9:36 AM, Zhengyu Gu wrote:
>>> Hi Vladimir,
>>>
>>>
>>> On 09/19/2017 12:14 PM, Vladimir Kozlov wrote:
>>>> Compilers also use a lot thread local ResourceArea - 
>>>> Thread::current()->resource_area() and NEW_RESOURCE_ARRAY() macro.
>>>> But thread local area is defined as mtThread:
>>>>
>>>> http://hg.openjdk.java.net/jdk10/hs/hotspot/file/5ab7a67bc155/src/share/vm/runtime/thread.cpp#l218 
>>>
>>>
>>>
>>>
>>> Thread's resource area is general purpose per-thread storage and used 
>>> by many subsystems. Unfortunately, NMT has no way to distinguish the 
>>> users at this moment, categorizing as mThread is sort of placeholder.
>>>
>>> I am welcome to any suggestions
>>
>> Thread() is called from CompilerThread() and we can pass a parameter 
>> to indicate user. Or add a virtual method to Thread class to check 
>> type of thread.
>>
>> In the past we had compiler local changes to get information how much 
>> memory was used during compilation but it was never get pushed. We 
>> accessed Arena::_bytes_allocated for that.
>>
>> Thanks,
>> Vladimir
>>
>>>
>>> Thanks,
>>>
>>> -Zhengyu
>>>
>>>
>>>>
>>>>
>>>> Vladimir
>>>>
>>>> On 9/18/17 12:17 PM, Zhengyu Gu wrote:
>>>>> Compiler (C2) uses ResourceArea instead of Arena in some 
>>>>> circumstances, so it can take advantage of ResourceMark. However, 
>>>>> ResourceArea is tagged as mtThread, that results those memory is 
>>>>> miscounted by NMT
>>>>>
>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8187629
>>>>> Webrev: http://cr.openjdk.java.net/~zgu/8187629/webrev.00/
>>>>>
>>>>>
>>>>> Test:
>>>>>
>>>>>    hotspot_tier1 (fastdebug and release) on Linux x64
>>>>>
>>>>>
>>>>> Thanks,
>>>>>
>>>>> -Zhengyu