RFR: 8330198: Add some class loading related perf counters to measure VM startup [v2]

[Calvin Cheung]

On Fri, 10 May 2024 22:58:25 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Calvin Cheung has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:
>> 
>>  - Merge branch 'master' into xloginit-classloading
>>  - fix build issues on macos-x64 and -aarch64
>>  - Merge branch 'master' into xloginit-classloading
>>  - fix linux-x86 and minimal build issues
>>  - 8330198: Add some class loading related perf counters to measure VM startup
>
> src/hotspot/share/runtime/java.cpp line 245:
> 
>> 243: #else
>> 244: 
>> 245: void print_method_invocation_histogram() {}
> 
> Is this change necessary?

No, I've removed it.

> src/hotspot/share/runtime/perfData.hpp line 420:
> 
>> 418:     inline void inc(jlong val) { (*(jlong*)_valuep) += val; }
>> 419:     inline void dec(jlong val) { inc(-val); }
>> 420:     inline void reset() { (*(jlong*)_valuep) = 0; }
> 
> This new function doesn't seem to be used.

Removed.

> src/hotspot/share/runtime/perfData.hpp line 835:
> 
>> 833:   public:
>> 834:     inline PerfTraceTime(PerfLongCounter* timerp, bool is_on = true) : _timerp(timerp) {
>> 835:       if (!is_on || !UsePerfData) return;
> 
> Instead of having a separate `is_on` parameter, can we check for `timerp == nullptr1` instead?

It works. I've pushed another commit.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/18790#discussion_r1599184407
PR Review Comment: https://git.openjdk.org/jdk/pull/18790#discussion_r1599184566
PR Review Comment: https://git.openjdk.org/jdk/pull/18790#discussion_r1599184469