Integrated: 8346568: G1: Other time can be negative

Sangheon Kim sangheki at openjdk.org
Wed Apr 23 16:40:00 UTC 2025


On Fri, 4 Apr 2025 18:00:21 GMT, Sangheon Kim <sangheki at openjdk.org> wrote:

> Other time described in this bug is displayed at G1GCPhaseTimes::print_other(total_measured_time - sum_of_sub_phases). And the value can be negative for 3 reasons.
> 1. Different scope of measurement
>     - 3 variables is out of scope from total_measured_time. Those used for wait-root-region-scan, verify-before/after. 
>        (_root_region_scan_wait_time_ms, _cur_verify_before_time_ms and _cur_verify_after_time_ms)
>     - Changed not to be included in sum_of_sub_phases.
>     - One may want to include them in total_measured_time but I think it is better to be addressed in a separate ticket. 
> 2. Duplicated measurement
>     - Initial and optional evacuation time include nmethod-cleanup-time, so separated them as we are already measuring them. As there is no public getter, just added cleanup time when those evacuation time are used internally.
> 3. Pre Concurrent task execution time
>     - Sometimes the difference between the existing average time and pre-concurrent work is 2 digit milliseconds. Changed to measure exact time rather than accumulating the average value to sum_of_sub_phases and keep displaying concurrent tasks' average execution time.
> 
> Testing: tier 1 ~ 5

This pull request has now been integrated.

Changeset: 8bd56452
Author:    Sangheon Kim <sangheki at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/8bd564521804e98911cc9ff3b7696165e3243139
Stats:     68 lines in 4 files changed: 36 ins; 20 del; 12 mod

8346568: G1: Other time can be negative

Reviewed-by: tschatzl, iwalulya

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PR: https://git.openjdk.org/jdk/pull/24454


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