RFR: JDK-8296931: NMT tests slowed down considerably by JDK-8242181

[Thomas Stuefe]

We noticed that NMT tests on our slower PPC machines started failing.

The reason is that NMT detail reports have become 2-5x slower. This is caused by us now parsing the dwarf debug information to extract source information for each PC in each call stack. That is nice but costly.

The slowdown is not limited to PPC, it affects all Elf platforms. On my Linux x64 box, runtime/NMT/VirtualAllocCommitMerge.java increased from 20 to 90 seconds.

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This patch simply removes source info from NMT call stacks. They are not that important for pinpointing leaks and such. I considered more involved solutions, like making them optional via an argument to the NMT report command, but decided against it. The added benefit would be small, not worth much complexity.

With this patch, on my box with -conc 4 all NMT together are about 2.5 x faster (2m56 -> 1m09).

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Commit messages:
 - disable NMT stack printing

Changes: https://git.openjdk.org/jdk/pull/11135/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11135&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8296931
  Stats: 5 lines in 1 file changed: 1 ins; 1 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/11135.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11135/head:pull/11135

PR: https://git.openjdk.org/jdk/pull/11135