RFR: 8241361: ZGC: Implement memory related JFR events

[Erik Österlund]

Hi Stefan,

Still good.

Thanks,
/Erik

On 2020-03-30 17:32, Stefan Karlsson wrote:
> Updated webrevs:
>  https://cr.openjdk.java.net/~stefank/8241361/webrev.04.delta/
>  https://cr.openjdk.java.net/~stefank/8241361/webrev.04/
>
> Changes after some testing and discussions with Per:
>
> 1) For some reason it's required by JFR testing that the .jfc files 
> list the stackTrace value. Fixed that.
> 2) Only generate ZUncommit when we actually have uncommitted memory.
> 3) Send relocation set group events for large pages.
> 4) Turn off both logging and event generation when medium pages have 
> been disabled.
>
> Thanks,
> StefanK
>
> On 2020-03-20 14:43, Stefan Karlsson wrote:
>> Hi all,
>>
>> Please review this patch to add some memory related JFR events to ZGC.
>>
>> https://cr.openjdk.java.net/~stefank/8241361/webrev.01/
>> https://bugs.openjdk.java.net/browse/JDK-8241361
>>
>> Added events:
>>
>> ZAllocationStall - Record when we run out of heap memory and the Java 
>> threads stall, waiting for the GC to free up memory.
>>
>> ZPageAllocation - Updated the existing event to also record the 
>> duration of the event. Updated the event to only be reported if the 
>> allocation takes longer than 1 ms.
>>
>> ZPageCacheFlush - Record when the page cache needs to be flushed. 
>> This usually happens when we run out of a specific page size and have 
>> to detach the physical and virtual memory to materialize a new ZPage. 
>> We also flush pages when we uncommit memory.
>>
>> ZRelocationSet - Record information about the selected relocation set.
>>
>> ZUncommit - Record when we uncommit and hand back memory to the OS.
>>
>> The patch also contains some small cosmetic changes to existing 
>> events, whitespace fixes.