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

[David Holmes]

On Thu, 19 Jan 2023 20:43:11 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

test/jdk/java/lang/invoke/VarHandles/VarHandleTestAccessBoolean.java line 284:

> 282: 
> 283:     // CompileThresholdScaling is set to 0.1 and ITERS to 2000 to reduce
> 284:     // the test execution

Wouldn't this be clearer as an `@comment` in the test header prior to the `@run` statements that use the variables?

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