RFR: 8336410: runtime/NMT/TotalMallocMmapDiffTest.java Total malloc diff is incorrect. Expected malloc diff range

[Johan Sjölen]

On Sun, 28 Jul 2024 07:49:35 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> Hi,
>> 
>> We've seen intermittent failures in this test because of the change being out of the pre-defined range. The largest "out of bounds" we've observed is 1.5MiB, so increasing the fudge factor to allow for 25MiBs more/less should be sufficient for us to not see this error for a while. This kind of adjustment is an unfortunate necessity when developing these kinds of tests.
>
> Ping 
> 
>> Should we consider splitting the fudge factor into 2 - one for lower bound, the other for upper one?
>> 
>> I can see how the lower bound should be tighter, whereas the upper one might be harder to define and we might need to keep upping?
> 
> That sounds reasonable. 
> 
> In addition, consider running the test with C1 only, to remove C2 and its arenas out of the equation.

@tstuefe , @gerard-ziemski , ping for approval!

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PR Comment: https://git.openjdk.org/jdk/pull/20326#issuecomment-2256142341