RFR: JDK-8317772: NMT: Make peak values available in release builds

[Zhengyu Gu]

On Tue, 10 Oct 2023 12:18:15 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> We added peak counts to NMT with [JDK-8297958](https://bugs.openjdk.org/browse/JDK-8297958). That feature is *extremely* helpful in analyzing native memory footprints since it gives you a glance into the past. For instance, it makes libc memory retention easier to explain.
> 
> Initially, I restricted this feature to debug JVMs out of vague concerns about performance when running with NMT. However, after measuring, it turns out that the increase in cost is very small. This makes sense since we only update the peak values when we actually reach a peak. 
> 
> Since the payoff is huge, it makes sense to have this feature always enabled. We don't need a new switch for that. As a side effect, NMT code becomes a bit clearer since we can lose a number of assert ifdefs.

LGTM

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Marked as reviewed by zgu (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/16119#pullrequestreview-1674081345