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

[Zhengyu Gu]

Thanks for the review, Vladimir.

-Zhengyu

On 09/19/2017 01:56 PM, Vladimir Kozlov wrote:
> 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