RFR: 8258912: Remove JVM options CountJNICalls and CountJVMCalls

[David Holmes]

On 13/01/2021 12:38 pm, David Holmes wrote:
> On Tue, 12 Jan 2021 15:17:52 GMT, Harold Seigel <hseigel at openjdk.org> wrote:
> 
>> Please review this change to remove the old non-product JVM -XX flags CountRuntimeCalls, CountJNICalls, CountJVMCalls, and CountRemovableExceptions.  Additionally, this change removes non-product flag WarnOnStalledSpinLock because, as a result of this change, it is no longer used.
>>
>> The change was tested with Mach5 tiers 1-2 on Linux, Mac OS, and Windows, and tiers 3-5 on Linux x64.
>>
>> Thanks, Harold
> 
> Hi Harold,
> 
> The call counters seem like useful statistics to me, though ones that may only be checked during specific types of development work. I think some consultation may be in order here rather than "take it away and see if anyone complains".
> 
> At a minimum I'd like to know whether our benchmarking/optimisation experts ever utilise these when figuring out code changes - paging @cl4es and @shipilev  :)

Seems Claes and Alexey are okay with removing these. I don't know who 
else may use them. If it turns out to be an issue we can revert, but 
there are probably better means of profiling (though this one is simple 
and lightweight).

Thanks,
David

> Thanks,
> David
> 
> -------------
> 
> PR: https://git.openjdk.java.net/jdk/pull/2050
>