RFR: 8187809: UseMembar should be set true and deprecate the flag

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RFR: 8187809: UseMembar should be set true and deprecate the flag

Robbin Ehn
Hi all, please review!

This patch set the default technique for reading thread state to memory barriers instead of using the asymmetric dekker
synchronization on all platforms. We also deprecate the option and starting the removal process. There have been
discussion with people involved in all platforms and we will have another discussion before obsoleting the flag to make
sure no issue have been found.

More info in CSR:
https://bugs.openjdk.java.net/browse/JDK-8187812

Bug:
https://bugs.openjdk.java.net/browse/JDK-8187809

Code:
http://cr.openjdk.java.net/~rehn/8187809/webrev/

Thanks, Robbin
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Re: RFR: 8187809: UseMembar should be set true and deprecate the flag

Robbin Ehn
Hi,

I forgot to say, UseMembar have been tested heavily on our supported platforms.
This particular changeset just passed sanity test of tier 1-2.

Thanks, Robbin

On 2017-11-08 21:48, Robbin Ehn wrote:

> Hi all, please review!
>
> This patch set the default technique for reading thread state to memory barriers instead of using the asymmetric dekker
> synchronization on all platforms. We also deprecate the option and starting the removal process. There have been
> discussion with people involved in all platforms and we will have another discussion before obsoleting the flag to make
> sure no issue have been found.
>
> More info in CSR:
> https://bugs.openjdk.java.net/browse/JDK-8187812
>
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8187809
>
> Code:
> http://cr.openjdk.java.net/~rehn/8187809/webrev/
>
> Thanks, Robbin
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Re: RFR: 8187809: UseMembar should be set true and deprecate the flag

Daniel D. Daugherty
On 11/8/17 3:52 PM, Robbin Ehn wrote:

> Hi,
>
> I forgot to say, UseMembar have been tested heavily on our supported
> platforms.
> This particular changeset just passed sanity test of tier 1-2.
>
> Thanks, Robbin
>
> On 2017-11-08 21:48, Robbin Ehn wrote:
>> Hi all, please review!
>>
>> This patch set the default technique for reading thread state to
>> memory barriers instead of using the asymmetric dekker
>> synchronization on all platforms. We also deprecate the option and
>> starting the removal process. There have been discussion with people
>> involved in all platforms and we will have another discussion before
>> obsoleting the flag to make sure no issue have been found.
>>
>> More info in CSR:
>> https://bugs.openjdk.java.net/browse/JDK-8187812
>>
>> Bug:
>> https://bugs.openjdk.java.net/browse/JDK-8187809
>>
>> Code:
>> http://cr.openjdk.java.net/~rehn/8187809/webrev/

src/hotspot/cpu/ppc/globals_ppc.hpp
src/hotspot/cpu/s390/globals_s390.hpp
src/hotspot/cpu/sparc/globals_sparc.hpp
src/hotspot/cpu/x86/globals_x86.hpp
     No comments.

src/hotspot/share/runtime/arguments.cpp
     No comments on your change.
     The existing inconsistent indents in those columns are annoying.

Thumbs up.

Dan


>>
>> Thanks, Robbin

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Re: RFR: 8187809: UseMembar should be set true and deprecate the flag

Robbin Ehn
Thanks Dan!

/Robbin

On 2017-11-08 22:16, Daniel D. Daugherty wrote:

> On 11/8/17 3:52 PM, Robbin Ehn wrote:
>> Hi,
>>
>> I forgot to say, UseMembar have been tested heavily on our supported platforms.
>> This particular changeset just passed sanity test of tier 1-2.
>>
>> Thanks, Robbin
>>
>> On 2017-11-08 21:48, Robbin Ehn wrote:
>>> Hi all, please review!
>>>
>>> This patch set the default technique for reading thread state to memory barriers instead of using the asymmetric
>>> dekker synchronization on all platforms. We also deprecate the option and starting the removal process. There have
>>> been discussion with people involved in all platforms and we will have another discussion before obsoleting the flag
>>> to make sure no issue have been found.
>>>
>>> More info in CSR:
>>> https://bugs.openjdk.java.net/browse/JDK-8187812
>>>
>>> Bug:
>>> https://bugs.openjdk.java.net/browse/JDK-8187809
>>>
>>> Code:
>>> http://cr.openjdk.java.net/~rehn/8187809/webrev/
>
> src/hotspot/cpu/ppc/globals_ppc.hpp
> src/hotspot/cpu/s390/globals_s390.hpp
> src/hotspot/cpu/sparc/globals_sparc.hpp
> src/hotspot/cpu/x86/globals_x86.hpp
>      No comments.
>
> src/hotspot/share/runtime/arguments.cpp
>      No comments on your change.
>      The existing inconsistent indents in those columns are annoying.
>
> Thumbs up.
>
> Dan
>
>
>>>
>>> Thanks, Robbin
>
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Re: RFR: 8187809: UseMembar should be set true and deprecate the flag

serguei.spitsyn@oracle.com
In reply to this post by Robbin Ehn
Hi Robbin,

Looks good.

Thanks,
Serguei

On 11/8/17 12:52, Robbin Ehn wrote:

> Hi,
>
> I forgot to say, UseMembar have been tested heavily on our supported
> platforms.
> This particular changeset just passed sanity test of tier 1-2.
>
> Thanks, Robbin
>
> On 2017-11-08 21:48, Robbin Ehn wrote:
>> Hi all, please review!
>>
>> This patch set the default technique for reading thread state to
>> memory barriers instead of using the asymmetric dekker
>> synchronization on all platforms. We also deprecate the option and
>> starting the removal process. There have been discussion with people
>> involved in all platforms and we will have another discussion before
>> obsoleting the flag to make sure no issue have been found.
>>
>> More info in CSR:
>> https://bugs.openjdk.java.net/browse/JDK-8187812
>>
>> Bug:
>> https://bugs.openjdk.java.net/browse/JDK-8187809
>>
>> Code:
>> http://cr.openjdk.java.net/~rehn/8187809/webrev/
>>
>> Thanks, Robbin

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Re: RFR: 8187809: UseMembar should be set true and deprecate the flag

David Holmes
In reply to this post by Robbin Ehn
Looks good.

One nit below ...

On 9/11/2017 6:48 AM, Robbin Ehn wrote:
> Hi all, please review!
>
> This patch set the default technique for reading thread state to memory
> barriers instead of using the asymmetric dekker synchronization on all
> platforms.

That's not quite an accurate description. The option is to use platform
memory barriers (+UseMembar) or the memory-serialization-page
"simulated" memory barrier. We still employ asymmetric Dekker
synchronization.

Thanks,
David

> We also deprecate the option and starting the removal
> process. There have been discussion with people involved in all
> platforms and we will have another discussion before obsoleting the flag
> to make sure no issue have been found.
>
> More info in CSR:
> https://bugs.openjdk.java.net/browse/JDK-8187812
>
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8187809
>
> Code:
> http://cr.openjdk.java.net/~rehn/8187809/webrev/
>
> Thanks, Robbin
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Re: RFR: 8187809: UseMembar should be set true and deprecate the flag

Robbin Ehn
In reply to this post by serguei.spitsyn@oracle.com
Thanks Serguei!

/Robbin

On 11/09/2017 01:50 AM, [hidden email] wrote:

> Hi Robbin,
>
> Looks good.
>
> Thanks,
> Serguei
>
> On 11/8/17 12:52, Robbin Ehn wrote:
>> Hi,
>>
>> I forgot to say, UseMembar have been tested heavily on our supported platforms.
>> This particular changeset just passed sanity test of tier 1-2.
>>
>> Thanks, Robbin
>>
>> On 2017-11-08 21:48, Robbin Ehn wrote:
>>> Hi all, please review!
>>>
>>> This patch set the default technique for reading thread state to memory
>>> barriers instead of using the asymmetric dekker synchronization on all
>>> platforms. We also deprecate the option and starting the removal process.
>>> There have been discussion with people involved in all platforms and we will
>>> have another discussion before obsoleting the flag to make sure no issue have
>>> been found.
>>>
>>> More info in CSR:
>>> https://bugs.openjdk.java.net/browse/JDK-8187812
>>>
>>> Bug:
>>> https://bugs.openjdk.java.net/browse/JDK-8187809
>>>
>>> Code:
>>> http://cr.openjdk.java.net/~rehn/8187809/webrev/
>>>
>>> Thanks, Robbin
>
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Re: RFR: 8187809: UseMembar should be set true and deprecate the flag

Robbin Ehn
In reply to this post by David Holmes
Thanks David!

/Robbin


On 11/09/2017 02:48 AM, David Holmes wrote:

> Looks good.
>
> One nit below ...
>
> On 9/11/2017 6:48 AM, Robbin Ehn wrote:
>> Hi all, please review!
>>
>> This patch set the default technique for reading thread state to memory
>> barriers instead of using the asymmetric dekker synchronization on all platforms.
>
> That's not quite an accurate description. The option is to use platform memory
> barriers (+UseMembar) or the memory-serialization-page "simulated" memory
> barrier. We still employ asymmetric Dekker synchronization.
>
> Thanks,
> David
>
>> We also deprecate the option and starting the removal process. There have been
>> discussion with people involved in all platforms and we will have another
>> discussion before obsoleting the flag to make sure no issue have been found.
>>
>> More info in CSR:
>> https://bugs.openjdk.java.net/browse/JDK-8187812
>>
>> Bug:
>> https://bugs.openjdk.java.net/browse/JDK-8187809
>>
>> Code:
>> http://cr.openjdk.java.net/~rehn/8187809/webrev/
>>
>> Thanks, Robbin