RFR(M): 8017317: PPC64 (part 7): cppInterpreter: implement support for biased locking

[David Holmes]

Sorry I've been in and out of the office this past week.

I think the move should happen - but whether that is easier to do before 
or after I can't say. I'll leave it to Vladimir to make the call.

David
-----

On 2/07/2013 6:41 PM, Lindenmaier, Goetz wrote:
> Hi David,
>
> can I push this change now?  Or will the files be moved?
> I prepared  a webrev without the shared change:
> http://cr.openjdk.java.net/~goetz/webrevs/8017317-lock-2/
>
> Best regards,
>    Goetz.
>
>
> -----Original Message-----
> From: ppc-aix-port-dev-bounces at openjdk.java.net [mailto:ppc-aix-port-dev-bounces at openjdk.java.net] On Behalf Of Vladimir Kozlov
> Sent: Freitag, 28. Juni 2013 00:07
> To: David Holmes
> Cc: ppc-aix-port-dev at openjdk.java.net; hotspot-dev at openjdk.java.net
> Subject: Re: RFR(M): 8017317: PPC64 (part 7): cppInterpreter: implement support for biased locking
>
> David,
>
> Do you insist on moving cppInterpreter files into separate directory? If
> yes, we need to do that in our main sources to avoid merges nightmare.
> And I will do the move.
>
> Thanks,
> Vladimir
>
> On 6/27/13 5:18 AM, David Holmes wrote:
>> Vladimir,
>>
>> On 27/06/2013 9:34 AM, Vladimir Kozlov wrote:
>>> Hi Goetz,
>>>
>>> On 6/26/13 7:30 AM, Lindenmaier, Goetz wrote:
>>>> Hi,
>>>>
>>>> To use biased locking in our PPC64 VM,we fixed the biased locking
>>>> implementation
>>>> in the cppInterpreter.  We also added  BiasedLockingStatistic support.
>>>
>>> Oracle does not use cppInterpreter and no building and testing are done.
>>> So we trust you to do testing of these changes.
>>> I glanced on these changes and they look fine to me.
>>>
>>> One suggestion I heard from David H. is to move cppInterpreter related
>>> files (all 6 of them) from interpreter/ directory to separate directory.
>>> So we can see when changes does not affect our shared code.
>>
>> It is a general source of confusion to new hotspot engineers that there
>> are actually two interpreters in one directory and that one is not used
>> by the historical primary ports. It also isn't obvious that
>> bytecodeInterpreter.cpp pertains to the cppInterpreter.
>>
>>>> We need an additional ordering operation in revoke_bias() when writing
>>>> the mark.
>>>
>>> Why you need ordering only for locked objects in this code? And why here
>>> at all? This code is executed at safepoint.
>>
>> There is one occurrence that is not executed at a safepoint - see
>> BiasedLocking::Condition BiasedLocking::revoke_and_rebias. Though it
>> seems to be operating only on current thread in that case.
>>
>> The use of release_set_mark seems consistent with other uses in
>> synchronizer.cpp.
>>
>> David
>> -----
>>
>>> thanks,
>>> Vladimir
>>>
>>>> The change enables biased locking for ppc64 per default.
>>>> http://cr.openjdk.java.net/~goetz/webrevs/8017317-lock/
>>>>
>>>> Please review and test this change.
>>>>
>>>> Best regards,
>>>>     Goetz
>>>>