RFR: 8272447: Remove 'native' ranked Mutex

[David Holmes]

On Mon, 16 Aug 2021 04:26:55 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> src/hotspot/share/runtime/mutexLocker.cpp line 338:
>> 
>>> 336:   def(ThreadsSMRDelete_lock        , PaddedMonitor, special,     true,  _safepoint_check_never);
>>> 337:   def(ThreadIdTableCreate_lock     , PaddedMutex  , leaf,        false, _safepoint_check_always);
>>> 338:   def(SharedDecoder_lock           , PaddedMutex  , tty-1,       true,  _safepoint_check_never);
>> 
>> Sorry I don't understand how this you moved this ranking from being ultra-high to being one of the lowest. What are you actually saying about this lock? What rules are you applying to determine what the rank should be?
>
> [not a review, just replying to @dholmes-ora] Mutex::native isn't an "ultra-high" rank, it is outside the ranking system.  Rank checks are not applied for Mutex::native.  See the occurrences of Mutex::native in mutex.cpp.

I stand corrected - thanks @kimbarrett  - but my question remains valid. If this was considered outside the ranking system then it was presumably because a suitable rank could not be determined, so what rules are now being used to determine this new rank?

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PR: https://git.openjdk.java.net/jdk/pull/5116