RFR (M): 8227434: G1 predictions may over/underflow with high variance input

Stefan Johansson stefan.johansson at oracle.com
Thu Nov 21 14:26:00 UTC 2019

Hi Thomas,

On 2019-11-12 15:10, Thomas Schatzl wrote:
> Hi all,
>    can I have reviews for this change that tries to fix possible 
> underflows and overflows in our predictor use in case there is high 
> variance input?
> I did not analyze for every case whether the issue actually happened, 
> but changed the get_new_prediction() calls to something I believe is 
> appropriate for the given sequence. Cases where there has already been 
> some clamping going on were obvious of course.
> It's a bit boring to review...
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8227434
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8227434/webrev/
Looks good in general, me and Thomas discussed some naming suggestions 
offline, but we are going to do that as a separate RFE. See JDK-8234574.


> Testing:
> hs-tier1-5
> Thanks,
>    Thomas

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