[15] RFR 8238633: JVMTI heap walk should consult GC for marking oops

[Zhengyu Gu]

Hi Serguei,


On 2/18/20 3:53 PM, serguei.spitsyn at oracle.com wrote:
> Hi Zhengyu,
> 
> It looks okay to me.
> The testing you do looks enough for verification.
> But I'm not sure about performance testing though.

Thanks for reviewing.

I asked around my colleagues, if they knew any benchmarks for JVMTI heap 
walk, the answer was 'no'. As Stefan mentioned, this is a slow piece of 
code, I doubt if there is any benchmarks for it.

I would appreciate it if any performance people can chip in.

Thanks,

-Zhengyu




> 
> Thanks,
> Serguei
> 
> 
> On 2/17/20 6:51 AM, Zhengyu Gu wrote:
>> Hi Stefan,
>>
>> Thanks for the review and suggestions, updated accordingly:
>>
>> http://cr.openjdk.java.net/~zgu/JDK-8238633/webrev.01/
>>
>>>
>>> ---
>>> Previously, the calls to 'mark' and 'visited' were inlineable, but 
>>> now every GC has to take a virtual call when marking the objects. My 
>>> guess is that this code is slow anyway, and that it doesn't matter 
>>> too much, but did you measure the effect of that change with, for 
>>> example, G1?
>>>
>> I did rough measurement, timing 
>> vmTestbase/nsk/jvmti/unit/heap/HeapWalkTests/TestDescription.java test.
>>
>> If you know any tests/benchmarks I should measure, please let me know.
>>
>> Thanks,
>>
>> -Zhengyu
>>
>>
>>> Thanks,
>>> StefanK
>>>
>>>> Test:
>>>>    hotspot_gc
>>>>    vmTestbase_nsk_jdi
>>>>    vmTestbase_nsk_jvmti
>>>>
>>>> Thanks,
>>>>
>>>> -Zhengyu
>>>>
>>>>
>>>
>>
>