RFR(S): 8237375: SimpleThresholdPolicy misses CounterDecay timestamp initialization

[Doerr, Martin]

Hi David,

thanks for the review. I'll push it after
https://bugs.openjdk.java.net/browse/JDK-8235741

Best regards,
Martin


> -----Original Message-----
> From: David Holmes <david.holmes at oracle.com>
> Sent: Mittwoch, 22. Januar 2020 12:52
> To: Doerr, Martin <martin.doerr at sap.com>; 'hotspot-compiler-
> dev at openjdk.java.net' <hotspot-compiler-dev at openjdk.java.net>
> Cc: Volker Simonis (volker.simonis at gmail.com) <volker.simonis at gmail.com>
> Subject: Re: RFR(S): 8237375: SimpleThresholdPolicy misses CounterDecay
> timestamp initialization
> 
> On 22/01/2020 8:47 pm, Doerr, Martin wrote:
> > Hi David,
> >
> > I'll change it to update_last_timestamp before pushing.
> > Can I add you as reviewer?
> 
> Sure.
> 
> Thanks,
> David
> 
> > Best regards,
> > Martin
> >
> >
> >> -----Original Message-----
> >> From: David Holmes <david.holmes at oracle.com>
> >> Sent: Montag, 20. Januar 2020 22:54
> >> To: Doerr, Martin <martin.doerr at sap.com>; 'hotspot-compiler-
> >> dev at openjdk.java.net' <hotspot-compiler-dev at openjdk.java.net>
> >> Cc: David Holmes <David.Holmes at oracle.com>
> >> Subject: Re: RFR(S): 8237375: SimpleThresholdPolicy misses CounterDecay
> >> timestamp initialization
> >>
> >> Hi Martin,
> >>
> >> On 21/01/2020 12:25 am, Doerr, Martin wrote:
> >>> Hi,
> >>>
> >>> I'd like to fix warmup issues we observed in test
> >>> compiler/c2/Test8004741.java.
> >>>
> >>> The issue is a missing timestamp initialization which leads to a
> >>> premature counter decay at the first safepoint with -XX:-
> >> TieredCompilation.
> >>>
> >>> Bug:
> >>>
> >>> https://bugs.openjdk.java.net/browse/JDK-8237375
> >>>
> >>> Webrev:
> >>>
> >>>
> http://cr.openjdk.java.net/~mdoerr/8237375_CounterDecay/webrev.00/
> >>>
> >>> The webrev applies on top of the preliminary fix for
> >>> https://bugs.openjdk.java.net/browse/JDK-8235741.
> >>>
> >>> I'll wait until that one gets pushed.
> >>>
> >>> What it changes:
> >>>
> >>>    * Move class CounterDecay up
> >>>    * Introduce reset_last_timestamp()
> >>
> >> "reset" suggests clearing or moving back to an original value to me. How
> >> about just "set" or "update"?
> >>
> >> Cheers,
> >> David
> >>
> >>>    * Use this function in decay() and in SimpleCompPolicy::initialize()
> >>>
> >>> Best regards,
> >>>
> >>> Martin
> >>>