RFR(S): 8227597: [fastdbg build] Arena::inc_bytes_allocated should get inlined

[Doerr, Martin]

Hi Götz and Matthias,

thanks for reviewing.

Right, using a simple addition instead of the atomics may allow more optimizations.
If nobody insists on treating the statistics values as volatile, I prefer this version:
http://cr.openjdk.java.net/~mdoerr/8227597_DBG_Inline_inc_bytes_allocated/webrev.01/

Best regards,
Martin


> -----Original Message-----
> From: Lindenmaier, Goetz
> Sent: Freitag, 12. Juli 2019 10:26
> To: Doerr, Martin <martin.doerr at sap.com>; hotspot-runtime-
> dev at openjdk.java.net
> Cc: Baesken, Matthias <matthias.baesken at sap.com>; Claes Redestad
> <claes.redestad at oracle.com>
> Subject: RE: RFR(S): 8227597: [fastdbg build] Arena::inc_bytes_allocated
> should get inlined
> 
> Hi Martin,
> 
> thanks for looking at the timeouts we get with the jtreg tests
> on ppc.  Inlining inc_bytes_allocated looks like a step forward.
> 
> But why do you remove the #if in inc_stat_counter()?
> It is not there because it's not implemented on other platforms,
> but because SPARC and X86 have (had) 32-bit variants.
> Actually, your change should slow down the code on
> PPC & others.
> 
> I think the right #define here is #ifndef LP64.
> And you now need that in inc_bytes_allocated, too.
> 
> Best,
>   Goetz.
> 
> 
> > -----Original Message-----
> > From: Doerr, Martin
> > Sent: Donnerstag, 11. Juli 2019 17:32
> > To: hotspot-runtime-dev at openjdk.java.net
> > Cc: Baesken, Matthias <matthias.baesken at sap.com>; Lindenmaier, Goetz
> > <goetz.lindenmaier at sap.com>; Claes Redestad
> <claes.redestad at oracle.com>
> > Subject: RFR(S): 8227597: [fastdbg build] Arena::inc_bytes_allocated should
> > get inlined
> >
> > Hi,
> >
> >
> >
> > the simple function Arena::inc_bytes_allocated can be found as CPU
> consuming
> > when profiling the fastdbg build. It is located in a cpp file.
> > It should better get inlined to improve the performance of the fastdbg VM
> > which is important for complex tests.
> > In addition, atomic 8-Byte load and store functions are available on all
> > platforms, so the "#if defined ..." can get removed.
> >
> >
> >
> > Here's my proposal:
> >
> >
> http://cr.openjdk.java.net/~mdoerr/8227597_DBG_Inline_inc_bytes_allocat
> ed
> > /webrev.00/
> >
> >
> >
> > Feedback is welcome.
> >
> >
> >
> > Best regards,
> >
> > Martin
> >
> >