RFR (S) 8219712: code_size2 is too small on new Skylake CPUs

[Langer, Christoph]

Ok, I've pushed to 12u as well. Thank you, Vladimir.

> -----Original Message-----
> From: hotspot-dev <hotspot-dev-bounces at openjdk.java.net> On Behalf Of
> Vladimir Kozlov
> Sent: Donnerstag, 28. Februar 2019 20:33
> To: hotspot-dev at openjdk.java.net
> Subject: Re: RFR (S) 8219712: code_size2 is too small on new Skylake CPUs
> 
> Since it is seen only in debug build it is not urgent. I agree to fix it in 12 update
> - I approved request.
> 
> Thanks,
> Vladimir
> 
> On 2/28/19 7:14 AM, Langer, Christoph wrote:
> > Hi,
> >
> > I've pushed Ralf's fix today after running it through the submit repo.
> >
> > As it seems to relate to JDK-8214074 (Optimize Ghash using AVX
> instructions) and this one is in jdk12, I guess it is quite urgent to bring this fix
> to jdk12 as well. We see the assertion in debug builds. And in the opt builds, I
> guess the memory would potentially be overwritten. How would you assess
> the urgency?
> >
> > Best regards
> > Christoph
> >
> >> -----Original Message-----
> >> From: hotspot-dev <hotspot-dev-bounces at openjdk.java.net> On Behalf
> Of
> >> David Holmes
> >> Sent: Dienstag, 26. Februar 2019 22:33
> >> To: Schmelter, Ralf <ralf.schmelter at sap.com>; HotSpot Open Source
> >> Developers <hotspot-dev at openjdk.java.net>
> >> Subject: Re: RFR (S) 8219712: code_size2 is too small on new Skylake CPUs
> >>
> >> Hi Ralf,
> >>
> >> webrev.1 looks good.
> >>
> >> Thanks,
> >> David
> >>
> >> On 27/02/2019 1:50 am, Schmelter, Ralf wrote:
> >>> Hi David,
> >>>
> >>>> I agree with Matthias: can this be a DEBUG_ONLY change?
> >>>
> >>> code_size2 is the size of the BufferBlob which is allocated to contain the
> >> "stub routines 2" created by StubGenerator. And in the debug build we
> >> check via assertions, that we don't overwrite the buffer. In the optimized
> >> version, we would later just overwrite part of the stub routines. So
> making it
> >> DEBUG_ONLY defeats the purpose of the change.
> >>>
> >>>> Further is the problem with 32-bit and 64-bit or only 64-bit? Your
> >>> change affects 32-bit.
> >>>
> >>> Since I only build the 64bit VM, I've changed the webrev:
> >> http://cr.openjdk.java.net/~rschmelter/webrevs/8219712/webrev.1/
> >>> It should now only increase the 64 bit version.
> >>>
> >>> In the end, it would be nice if the initial BufferBlob size could be more
> >> generous and then later adjusted to the really needed space, since it is
> really
> >> not easy to get a tight upper bound reliably, with it being dependent on
> the
> >> OS, GC, CPU features and other flags.
> >>>
> >>> Best regards,
> >>> Ralf
> >>>