RFR: 6203: Add ZGC allocation stall rule [v2]

[Suchita Chaturvedi]

On Fri, 18 Jul 2025 18:13:26 GMT, Suchita Chaturvedi <schaturvedi at openjdk.org> wrote:

>> This enhancement is to add new rule for ZGC Allocation Stall events.
>> 
>> The default configuration:
>>  
>> <img width="946" alt="image" src="https://github.com/user-attachments/assets/0d39ae26-fdc4-49e3-a0ed-fb7f7da8f709" />
>> 
>> Here are few screenshots for reference:
>> 
>> <img width="344" alt="image" src="https://github.com/user-attachments/assets/e7efe1e2-d6b3-4a05-8ea6-1bf2e8b8c15f" />
>> 
>> <img width="353" alt="image" src="https://github.com/user-attachments/assets/a3d3862f-96d2-4292-947f-4562c7f9f3d3" />
>> 
>> <img width="344" alt="image" src="https://github.com/user-attachments/assets/9616eea6-bce8-4395-a846-db343fe349f2" />
>> 
>> <img width="341" alt="image" src="https://github.com/user-attachments/assets/376a100e-ac05-48fe-a9c3-754923c3d79e" />
>> 
>> <img width="353" alt="image" src="https://github.com/user-attachments/assets/cfa7c5f1-08f0-44b4-a49d-28504439a631" />
>> 
>> Ignored
>> 
>> <img width="352" alt="image" src="https://github.com/user-attachments/assets/3c00c22e-e64d-46b0-8b64-ed653ed1fc4b" />
>> 
>> If we change default configuration as below:
>> 
>> <img width="367" alt="image" src="https://github.com/user-attachments/assets/8da64985-8446-44b8-bfb4-696a726b5255" />
>> 
>> <img width="350" alt="image" src="https://github.com/user-attachments/assets/ad89f02e-39b4-4df4-aae7-43cec9cc9a91" />
>> 
>> <img width="347" alt="image" src="https://github.com/user-attachments/assets/b3ec1081-26dd-4391-9e0f-0b4c64a7e3c1" />
>> 
>> <img width="344" alt="image" src="https://github.com/user-attachments/assets/106a7c3e-aaaf-495a-8c6f-281c96371e6e" />
>
> Suchita Chaturvedi has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Updated the rule as per new metric allocation stall rate

The new commit has the text update suggested by @jpbempel and the metric to calculate score is changed from allocation stall events count to stall rate. Also, I have added stall rate as part of rule result along with allocation stall count, total stall duration and maximum stall duration.

Here are the fresh screenshots:

<img width="617" height="489" alt="image" src="https://github.com/user-attachments/assets/681acef8-c13c-47df-988e-be6edec29032" />

<img width="344" height="224" alt="image" src="https://github.com/user-attachments/assets/d268029f-8161-4ed9-a716-681bd9fe99fd" />

<img width="353" height="223" alt="image" src="https://github.com/user-attachments/assets/9fad0538-ca6b-4265-9990-f1f9e9fcd5de" />

<img width="347" height="221" alt="image" src="https://github.com/user-attachments/assets/1f6c2bd1-87d4-411b-9f1c-489620cc2d68" />

<img width="347" height="221" alt="image" src="https://github.com/user-attachments/assets/e0dd209e-db01-418a-9d24-f95dacac1503" />

<img width="341" height="218" alt="image" src="https://github.com/user-attachments/assets/86435716-b774-4641-8d54-3d1254e0fddf" />

I will create a follow up enhancement to create a new rule for maximum stall duration metric.

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PR Comment: https://git.openjdk.org/jmc/pull/664#issuecomment-3090281834