RFR: 8330198: Add some class loading related perf counters to measure VM startup [v3]

[Calvin Cheung]

On Fri, 24 May 2024 06:59:32 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> If `UsePerfData` is set to false, `ProfileClassLinkage` is set to false in arguments.cpp:
>> 
>> 
>> 3761   if (ProfileClassLinkage && !UsePerfData) {
>> 3762     if (!FLAG_IS_DEFAULT(ProfileClassLinkage)) {
>> 3763        warning("Disabling ProfileClassLinkage since UsePerfData is turned off.");
>> 3764        FLAG_SET_DEFAULT(ProfileClassLinkage, false);
>> 3765      }
>> 3766   }
>> 
>> 
>> I will remove the extra parentheses.
>
> Yes but if  `UsePerfData` is true it doesn't mean `ProfileClassLinkage` is true.

The `_perf_classes_inited` counter is a pre-existing counter only depends on `UsePerfData`. The `ProfileClassLinkage` should not have any effect on the counter.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18790#discussion_r1614140958