RFR (S): 8181785: Remove the experimental ClearFPUAtPark JVM Flag

Robbin Ehn robbin.ehn at oracle.com
Fri Jun 9 12:36:32 UTC 2017


On 06/09/2017 02:27 PM, Thomas Schatzl wrote:
> Hi Erik,
> 
> On Thu, 2017-06-08 at 17:04 +0200, Erik Österlund wrote:
>> Hi,
>>
>> There is an experimental JVM flag called ClearFPUAtPark that is used
>> only by SPARC. It is turned off by default and is marked as Unsafe
>> and
>> Unstable.
>> The idea is to tell the Solaris kernel not to save floating point
>> registers when context switching.
>> I propose to remove it as it is an unstable option. It relies on an
>> implicit unstable OS contract with the kernel that may or may not be
>> honored.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8181785
>>
>> Webrev: http://cr.openjdk.java.net/~eosterlund/8181785/webrev.00/
>>
>> Testing: JPRT
>>
>> Will need a sponsor.
> 
>    looks good apart from copyright dates.
> 
> As even experimental VM options are part of the public VM interface, I
> think you need to do a CSR request.
> 
> Further I think we can't just remove these options but need to use the
> usual option deprecation/removal process.

Hi, here the runtime process:
http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2015-June/015277.html

     release 1: Deprecate & Handle - warn and keep supporting
     release 2: Deprecate & Obsolete - warn and do nothing
     release 3: Dead - unrecognized

But in this case I suggest going for 2 directly and let CSR guys object if so..

/Robbin

> 
> Thanks,
>    Thomas
> 


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