RFR: 8300693: Lower the compile threshold and reduce the iterations of warmup loop in VarHandles tests [v2]

[Paul Sandoz]

On Fri, 20 Jan 2023 17:45:46 GMT, Mandy Chung <mchung at openjdk.org> wrote:

>> `java/lang/invoke/VarHandles` tests run with C1, C2 and tiered compilations and the test cases are executed in the warm up loop with 20000 iterations to verify C1, C2 intrinsics.  Default Tier4CompileThreshold is 15000.
>> 
>> This PR proposes to scale the compile threshold to 0.1 such that the warm up loop can be reduced to 2000 iterations.  This will speed up the test execution time.
>> 
>> 
>> Before:
>> make test-only TEST=open/test/jdk/java/lang/invoke/VarHandles  341.06s user 14.65s system 563% cpu 1:03.14 total
>> 
>> After:
>> make test-only TEST=open/test/jdk/java/lang/invoke/VarHandles  234.38s user 13.08s system 535% cpu 46.218 total
>
> Mandy Chung has updated the pull request incrementally with one additional commit since the last revision:
> 
>   move the comment to @comment

Marked as reviewed by psandoz (Reviewer).

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PR: https://git.openjdk.org/jdk/pull/12104