[11u] RFR(S): 8241234: Unify monitor enter/exit runtime entries.

[gouessej at orange.fr]

Please can you elaborate about " there are enough other changes OpenJDK 11 lacks wrt. 11-oracle"?

 

 

> Message du 28/08/20 11:03
> De : "Lindenmaier, Goetz" 
> A : "'Severin Gehwolf'" , "Andrew Haley" , "Doerr, Martin" , "'hotspot-compiler-dev at openjdk.java.net'" , "jdk-updates-dev at openjdk.java.net" 
> Copie à : 
> Objet : RE: [11u] RFR(S): 8241234: Unify monitor enter/exit runtime entries.
> 
> Hi,
> 
> I'd prefer to push this.
> I'm not really happy with 11 staying behind 11-oracle in the JVMCI issue.
> Unfortunately there is nobody in the open community to address this.
> And there are enough other changes OpenJDK 11 lacks wrt. 11-oracle.
> If this gap grows big, we can no more claim OpenJDK 11 is a valid replacement
> for the Oracle vm. 
> 
> So I would continue to try to take all changes that go to 11-oracle
> to OpenJDK 11, too.
> 
> And as this is now ported to 11, let's push it.
> Anyways, it also affects C1 and other shared code, so it might
> simplify integrating follow-ups.
> 
> Best regards,
> Goetz.
> 
> 
> > -----Original Message-----
> > From: Severin Gehwolf 
> > Sent: Thursday, August 27, 2020 6:00 PM
> > To: Andrew Haley ; Doerr, Martin
> > ; 'hotspot-compiler-dev at openjdk.java.net'
> > ; jdk-updates-
> > dev at openjdk.java.net
> > Cc: Lindenmaier, Goetz 
> > Subject: Re: [11u] RFR(S): 8241234: Unify monitor enter/exit runtime entries.
> > 
> > On Thu, 2020-08-27 at 16:25 +0100, Andrew Haley wrote:
> > > Hi,
> > >
> > > On 27/08/2020 11:04, Doerr, Martin wrote:
> > > > > Why is anyone backporting a P4 Enhancement? Seems weird.
> > > > This is a good question in general. Personally, I'd vote for
> > > > backporting fewer less important things to 11u in the future. We
> > > > should better focus on 17 IMHO.
> > > >
> > > > However, there are some arguments for backporting this one:
> > > > - Oracle has done so. There may be more backports in this area and
> > > > I'd expect less effort if we have the same code in the open version.
> > > > - Performance is supposed to be better. (Though I didn't measure it.)
> > > > - New code is much cleaner. Let's keep in mind that we have to
> > > > support it for quite a while.
> > > >
> > > > Are you ok with it?
> > >
> > > I'm unsure. While "Oracle has backported it" has been a slam-dunk
> > > justification for many patches, I am concerned about the destabilizing
> > > effect of the volume of patches we are processing.
> > >
> > > "Better performance" is not in itself justification for a backport
> > > unless the improvement is really compelling.
> > >
> > > "Cleanups" are a red flag. The miserable history of code that has been
> > > broken by seemingly innocuous cleanups is long. This is a big change
> > > that affects some very delicate code, but the fact that there is
> > > already a GraalVM patch we can use is quite persuasive.
> > >
> > > So I'm not refusing it, I want people's opinions.
> > 
> > It seems like a nice-to-have fix for OpenJDK 11 itself. Interest seems
> > to be coming from Graal. Until there is a more compelling reason to
> > backport this (other than performance for some JVMCI impl) we shouldn't
> > backport this. We already have a label for these: jdk11u-jvmci-defer.
> > We should apply that and re-evaluate later if needed.
> > 
> > My $0.02
> > 
> > Thanks,
> > Severin
> 
>