RFR: 8366847: JFR reports incorrect number of cores on hybrid CPU [v5]

[Erik Gahlin]

On Wed, 8 Oct 2025 06:50:27 GMT, Yasumasa Suenaga <ysuenaga at openjdk.org> wrote:

>>> BTW I assume that "hwThreads" is the number of logical processors - right?
>> 
>> Yes
>
>> Perhaps better stated on the cores field:
> 
> Thanks for your comment! I added that sentence to `description` attribute in `Field` element.
> After this change, flight record contains following metadata. I believe it would be parsed in some tools like JMC (JMC shows the description as a tooltip)
> 
> 
> $ jfr metadata --events jdk.CPUInformation /tmp/test.jfr
> @Name("jdk.CPUInformation")
> @Category({"Operating System", "Processor"})
> @Label("CPU Information")
> @Description("Characteristics and descriptions of the processor(s) the JVM is running on")
> class CPUInformation extends jdk.jfr.Event {
>   @Label("Start Time")
>   @Timestamp("TICKS")
>   long startTime;
> 
>   @Label("Type")
>   String cpu;
> 
>   @Label("Description")
>   String description;
> 
>   @Unsigned
>   @Label("Sockets")
>   int sockets;
> 
>   @Unsigned
>   @Label("Cores")
>   @Description("Approximation on a hybrid CPU")
>   int cores;
> 
>   @Unsigned
>   @Label("Hardware Threads")
>   int hwThreads;
> }

Metadata looks good

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PR Review Comment: https://git.openjdk.org/jdk/pull/27080#discussion_r2412915309