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List:       openjdk-serviceability-dev
Subject:    RE: RFR(S) 8238585: Use handshake for JvmtiEventControllerPrivate::enter_interp_only_mode() and don'
From:       "Reingruber, Richard" <richard.reingruber () sap ! com>
Date:       2020-05-29 8:08:53
Message-ID: AM0PR0202MB3331548567160C6F712688859B8F0 () AM0PR0202MB3331 ! eurprd02 ! prod ! outlook ! com
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Thanks for the info, Vladimir, and for looking at the webrev.

Best regards,
Richard.

-----Original Message-----
From: Vladimir Kozlov <vladimir.kozlov@oracle.com> 
Sent: Donnerstag, 28. Mai 2020 18:03
To: Reingruber, Richard <richard.reingruber@sap.com>; \
serviceability-dev@openjdk.java.net; hotspot-compiler-dev@openjdk.java.net; \
                hotspot-runtime-dev@openjdk.java.net; hotspot-gc-dev@openjdk.java.net
Subject: Re: RFR(S) 8238585: Use handshake for \
JvmtiEventControllerPrivate::enter_interp_only_mode() and don't make compiled methods \
on stack not_entrant

Vladimir Ivanov is on break currently.
It looks good to me.

Thanks,
Vladimir K

On 5/26/20 7:31 AM, Reingruber, Richard wrote:
> Hi Vladimir,
> 
> > > Webrev: http://cr.openjdk.java.net/~rrich/webrevs/8238585/webrev.0/
> 
> > Not an expert in JVMTI code base, so can't comment on the actual changes.
> 
> > From JIT-compilers perspective it looks good.
> 
> I put out webrev.1 a while ago [1]:
> 
> Webrev:        http://cr.openjdk.java.net/~rrich/webrevs/8238585/webrev.1/
> Webrev(delta): http://cr.openjdk.java.net/~rrich/webrevs/8238585/webrev.1.inc/
> 
> You originally suggested to use a handshake to switch a thread into interpreter \
> mode [2]. I'm using a direct handshake now, because I think it is the best fit.
> 
> May I ask if webrev.1 still looks good to you from JIT-compilers perspective?
> 
> Can I list you as (partial) Reviewer?
> 
> Thanks, Richard.
> 
> [1] http://mail.openjdk.java.net/pipermail/serviceability-dev/2020-April/031245.html
>  [2] http://mail.openjdk.java.net/pipermail/serviceability-dev/2020-January/030340.html
>  
> -----Original Message-----
> From: Vladimir Ivanov <vladimir.x.ivanov@oracle.com>
> Sent: Freitag, 7. Februar 2020 09:19
> To: Reingruber, Richard <richard.reingruber@sap.com>; \
>                 serviceability-dev@openjdk.java.net; \
>                 hotspot-compiler-dev@openjdk.java.net
> Subject: Re: RFR(S) 8238585: Use handshake for \
> JvmtiEventControllerPrivate::enter_interp_only_mode() and don't make compiled \
> methods on stack not_entrant 
> 
> > Webrev: http://cr.openjdk.java.net/~rrich/webrevs/8238585/webrev.0/
> 
> Not an expert in JVMTI code base, so can't comment on the actual changes.
> 
> From JIT-compilers perspective it looks good.
> 
> Best regards,
> Vladimir Ivanov
> 
> > Bug:    https://bugs.openjdk.java.net/browse/JDK-8238585
> > 
> > The change avoids making all compiled methods on stack not_entrant when switching \
> > a java thread to interpreter only execution for jvmti purposes. It is sufficient \
> > to deoptimize the compiled frames on stack. 
> > Additionally a handshake is used instead of a vm operation to walk the stack and \
> > do the deoptimizations. 
> > Testing: JCK and JTREG tests, also in Xcomp mode with fastdebug and release \
> > builds on all platforms. 
> > Thanks, Richard.
> > 
> > See also my question if anyone knows a reason for making the compiled methods \
> > not_entrant: http://mail.openjdk.java.net/pipermail/serviceability-dev/2020-January/030339.html
> >  


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