RFR: 8273916: Remove 'special' ranking [v3]

[Patricio Chilano Mateo]

On Tue, 21 Sep 2021 12:07:06 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> This change removes the special ranking and folds it into nosafepoint.  You have to look at commit #3 to see this actual part of the change that doesn't include JDK-8273915.
>> This passes tier1-6 also.
>
> Coleen Phillimore has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains six commits:
> 
>  - Remove blank line.
>  - Merge branch 'master' into remove-special
>  - Add comment about ThreadSMRDelete_lock
>  - Remove "special" rank.
>  - Partition safepoint checking and nonchecking lock ranks.  The nonchecking locks are always lower ranked than the safepoint checking locks because they cannot block.
>  - Partition safepoint checking and nonchecking lock ranks.  The nonchecking locks are always lower ranked than the safepoint checking locks because they cannot block.

Hi Coleen,

Changes look good to me. Not straightforward to verify by code inspection but seems you also already figured out dependent locks with all the testing. 

Thanks,
Patricio

src/hotspot/share/runtime/mutexLocker.cpp line 228:

> 226:   def(StringDedupIntern_lock       , PaddedMutex  , nosafepoint, true,  _safepoint_check_never);
> 227:   def(ParGCRareEvent_lock          , PaddedMutex  , leaf,        true,  _safepoint_check_always);
> 228:   def(CodeCache_lock               , PaddedMonitor, nosafepoint-3, true,  _safepoint_check_never);

nit: There is a comment in mutexLocker.hpp that rank of CodeCache_lock is special.

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Marked as reviewed by pchilanomate (Committer).

PR: https://git.openjdk.java.net/jdk/pull/5563