RFR: 8257147: [TESTBUG] Set a larger default loop count for the VectorAPI jtreg tests

[Paul Sandoz]

On Fri, 4 Dec 2020 10:06:42 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

> The current default loop count of VectorAPI tests is too small (10 for load/store tests, 100 for arithmetic tests) to make the tests compiled with C2. This makes some potential issues not be reported as expected.
> 
> This patch fixes it by setting a larger default iteration.
> 
> The whole tests running time increases with this patch. Here is the results on two different types of machines:
> 
> Running with "`-conc:10`":
>              Before     After
> System A     5m30s      6m43s
> System B     5m1s       6m31s
> 
> Running with "`-conc:1`":
>              Before     After
> System A     26m52s     45m6s
> System B     30m3s      43m30s

It's good to revisit this, but I am concerned about the increase in test execution time. I wonder if we can approach this a little differently.

First, I think we should switch off tiered compilation, `-XX:-TieredCompilation` (maybe reconsider later some limited form of execution with tiered compilation enabled).
For such a configuration I observe, when using the current invocation count and looking at inline traces, far more lines with intrinsic `VectorSupport` methods.

Second, we could lower the compile threshold from 10000 e.g. `-XX:CompileThreshold=1000`. We can grep the inline trace and count the lines containing intrinsic `VectorSupport` methods.

Using both these approaches i think we can increase intrinsification without such a large increase in test execution time.

WDYT?

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PR: https://git.openjdk.java.net/jdk/pull/1621