Integrated: 8330198: Add some class loading related perf counters to measure VM startup

[Calvin Cheung]

On Tue, 16 Apr 2024 05:16:22 GMT, Calvin Cheung <ccheung at openjdk.org> wrote:

> Adding a few perf counters related to class loading to measure VM startup. The counters are only active if the user specifies `-Xlog:init` in the command line. A diagnostic flag `ProfileClassLinkage` is added to control the new counters. The flag is set to false by default and will be enabled if `-Xlog:init` is specified.
> 
> This change is already in the leyden/premain branch. There are more counters in the branch to measure other stuff. For now, just upstreaming class loader related counters.
> 
> Refer to the [comment](https://bugs.openjdk.org/browse/JDK-8330198?focusedId=14665311&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14665311) in the bug report for an example output.
> 
> Passed tiers 1 - 4 testing.

This pull request has now been integrated.

Changeset: eb2488fd
Author:    Calvin Cheung <ccheung at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/eb2488fd1781af49d936348d5f75731de2006ce7
Stats:     161 lines in 14 files changed: 145 ins; 7 del; 9 mod

8330198: Add some class loading related perf counters to measure VM startup

Co-authored-by: Vladimir Ivanov <vlivanov at openjdk.org>
Reviewed-by: iklam, dholmes

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PR: https://git.openjdk.org/jdk/pull/18790