jmx-dev RFR: JDK-8030957 - AIX: Implement OperatingSystemMXBean.getSystemCpuLoad() and .getProcessCpuLoad() on AIX

[Matthias Baesken]

On Tue, 20 May 2025 15:32:21 GMT, Suchismith Roy <sroy at openjdk.org> wrote:

> JBS Issue : [JDK-8030957](https://bugs.openjdk.org/browse/JDK-8030957)
> 
> These two methods should be implemented in src/aix/native/sun/management/AixOperatingSystem.c (which has to be created).
> 
> getProcessCpuLoad() can be probably implemented in the same way like on Solaris be reading /proc/self/psinfo
> 
> For getSystemCpuLoad() we'll probalby have to use 'perfstat_cpu_total()' from libperf (see http://publib.boulder.ibm.com/infocenter/pseries/v5r3/topic/com.ibm.aix.prftools/doc/prftools/prftools07.htm#wq407)
> 
> Once this issue has been resolved you should not forget to remove the two excludes from jdk/test/ProblemList.txt:
> 
> com/sun/management/OperatingSystemMXBean/GetProcessCpuLoad.java aix-all
> com/sun/management/OperatingSystemMXBean/GetSystemCpuLoad.java aix-all

Are you sure the perfstat functionality is always available ? 
In HS we do dynamic resolution (see e.g. os_perf_aix.cpp), but maybe that was needed long time ago and is not really needed any more? But please check this .

If we only address minimum AIX 7.2 we can probably simplify this approach or even go away from the current dynamic loading approach.
See also https://bugs.openjdk.org/browse/JDK-8222719  where I did already some cleanup (but kept the  AIX 7.1 vs. 7.2 ) .

There is still an fflush(stdout);  in UnixOperatingSystem.c  - guess this is not needed any more?

Maybe you can check the system tools you mentioned with 'trace' or 'tprof' or something similar to find out more about what they do and why they differ?

src/jdk.management/aix/native/libmanagement_ext/UnixOperatingSystem.c line 57:

> 55: 
> 56:     ret = perfstat_cpu_total(NULL, &cpu_total, sizeof(perfstat_cpu_total_t), 1);
> 57:     if (ret <= 0) {

I noticed that we check for retval < 0 in os_perf_aix.cpp, should we align this in some way ?

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PR Comment: https://git.openjdk.org/jdk/pull/25332#issuecomment-2896875648
PR Comment: https://git.openjdk.org/jdk/pull/25332#issuecomment-3048932756
PR Comment: https://git.openjdk.org/jdk/pull/25332#issuecomment-3056023114
PR Comment: https://git.openjdk.org/jdk/pull/25332#issuecomment-3106958683
PR Review Comment: https://git.openjdk.org/jdk/pull/25332#discussion_r2099545296