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

Erik Osterlund erik.osterlund at oracle.com
Fri Jun 9 17:03:28 UTC 2017


Thank you Robbin.

/Erik

> On 9 Jun 2017, at 18:27, robbin.ehn <robbin.ehn at oracle.com> wrote:
> 
> 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
> >>> 
> > 
> 


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