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

[David Holmes]

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
>