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List:       openjdk-hotspot-runtime-dev
Subject:    Re: RFR (S): 8181785: Remove the experimental ClearFPUAtPark JVM Flag
From:       Erik Osterlund <erik.osterlund () oracle ! com>
Date:       2017-06-09 17:02:55
Message-ID: 9976F529-4CC5-4BB4-90EE-AE571541F471 () oracle ! com
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Thank you Dan.

/Erik

> On 9 Jun 2017, at 18:29, Daniel D. Daugherty <daniel.daugherty@oracle.com> wrote:
> 
> I agree. Primary reason is that it is experimental. Secondary reasons
> are "unsafe" and "unstable".
> 
> Dan
> 
> 
> > On 6/9/17 10:23 AM, Erik Osterlund wrote:
> > 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@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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