RFR: 8236073: G1: Use SoftMaxHeapSize to guide GC heuristics

[Liang Mao]

Hi Thomas,

Do you have any testing result of the patch? 
I made a little change based on your webrev:
http://cr.openjdk.java.net/~tschatzl/8236073/webrev.2/
to retain the shrink in remark which fixed the failure of
JEP 346 and should handle the "idle" scenario.

http://cr.openjdk.java.net/~luchsh/8236073.webrev.5/

Thanks,
Liang






------------------------------------------------------------------
From:Thomas Schatzl <thomas.schatzl at oracle.com>
Send Time:2020 Feb. 19 (Wed.) 18:56
To:"MAO, Liang" <maoliang.ml at alibaba-inc.com>; Stefan Johansson <stefan.johansson at oracle.com>; hotspot-gc-dev <hotspot-gc-dev at openjdk.java.net>
Subject:Re: RFR: 8236073: G1: Use SoftMaxHeapSize to guide GC heuristics

Hi,

On 19.02.20 11:44, Liang Mao wrote:
> Hi Thomas,
> 
> When I was testing those benchmarks like specjbb2015 and specjvm2008,
> the expansions mostly happened at remark. So I guess the expansion after
> concurrent mark at peak usage based on a minimal capacity might
> prevent several expansions in normal young collections. It's only my
> thinking since I don't have much performance data. I don't have any
> problems with expanding after young collection:)

We'll collect perf data about this.

> 
> BTW, do you and Stefan prefer to leave the shrink at remark for fixing
> the failure of JEP346 and handling the idle scenario?

Yes, and since Stefan suggested that we should shrink during Remark 
already I think he agrees.

Thomas