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

[robbin.ehn]

Yes, ship it!
/Robbin
-------- Originalmeddelande --------Från: Erik Osterlund <erik.osterlund at oracle.com> Datum: 2017-06-09  18:23  (GMT+01:00) Till: daniel.daugherty at oracle.com Kopia: Robbin Ehn <robbin.ehn at oracle.com>, Thomas Schatzl <thomas.schatzl at oracle.com>, Hotspot dev runtime <hotspot-runtime-dev at openjdk.java.net> Rubrik: Re: RFR (S): 8181785: Remove the experimental ClearFPUAtPark JVM Flag 
Hi Thomas, Dan and Robbin,

Thank you for reviewing. As Dan pointed out - this JVM flag has always been advertised as unsafe and unstable, hence nobody should be using it.

Do we agree we are okay with removing it without a CCC/CSR request?

Thanks,
/Erik

> On 9 Jun 2017, at 17:06, Daniel D. Daugherty <daniel.daugherty at oracle.com> wrote:
> 
> We have removed several experimental options without a CCC/CSR request.
> This one is identified as:
> 
> experimental(intx, ClearFPUAtPark, 0, "(Unsafe, Unstable)")
> 
> Since it is flagged as "Unsafe" and "Unstable" (like one or two I removed
> in JDK9), no one should be using it. It will not be noticed or missed.
> 
> Dan
> 
> 
> 
>> On 6/9/17 6:36 AM, Robbin Ehn wrote:
>>> 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
>>> 
>