RFR: 8224974: Implement JEP 352

[Dmitry Chuyko]

Hi Andrew,

One quick question about synchronization in unmappers. One of 
preliminary steps for Loom was to replace monitor usage by j.u.c locks 
for I/O to let fibers release carrier threads. For instance see 
JDK-8222774. Does it make sense to do the same in your new unmappers code?

-Dmitry

[1] https://bugs.openjdk.java.net/browse/JDK-8222774

On 8/6/19 4:57 PM, Andrew Dinn wrote:
> On 06/08/2019 13:44, Aleksey Shipilev wrote:
>> Ah, that is exactly what I wanted. Good then, scratch the rest of my comments.
>> . . .
>> I thought that translating two separate (and statically bound) Unsafe calls, hooking them up to
>> separate Unsafe leaf entries, and then suddenly going into a single StubRoutine call with dynamic
>> argument that dispatches at runtime is a bit awkward. I would have expected it to end up with two
>> separate StubRoutines as well. Again, I have no strong opinion about this.
> Ok, thanks for clarifying. Inertia dictates I leave the stubs as is :-)
>
>> Yes, this looks cleaner. The declarations can be a bit less crowded:
>>
>>    static address data_cache_writeback()      { return _data_cache_writeback; }
>>    static address data_cache_writeback_sync() { return _data_cache_writeback_sync; }
>>
>>    typedef void (*DataCacheWritebackStub)(void *);
>>    static DataCacheWritebackStub DataCacheWriteback_stub()         { return ...
>>
>>    typedef void (*DataCacheWritebackSyncStub)(bool);
>>    static DataCacheWritebackSyncStub DataCacheWritebackSync_stub() { return ...
>>    . . .
>>>    http://cr.openjdk.java.net/~adinn/8224974/webrev.11
>> Looks good.
> Ok, I'll fold this and the other format errors you identified into the
> next patch.
>
>
> If I could please get a nod from Alan Bateman (and assuming I don't
> receive further comments from other reviewers) I'll push that next patch.
>
> Any more for any more ... ?
>
> regards,
>
>
> Andrew Dinn
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