On Wed, 5 May 2021 05:57:55 GMT, Hao Tang
<[email protected]> wrote:
>> src/jdk.management/unix/classes/com/sun/management/internal/OperatingSystemImpl.java
>> line 142:
>>
>>> 140: long usageNanos = containerMetrics.getCpuUsage();
>>> 141: if (numPeriods > 0 && usageNanos > 0) {
>>> 142: long quotaNanos =
>>> TimeUnit.MICROSECONDS.toNanos(quota * numPeriods);
>>
>> We happened to hit an exactly similar problem when running on a container
>> with openjdk15.
>>
>> Given we effectively agree that the problem is `elapsedNanos` doesn't
>> accurately reflect the cpu time allocated across all shares vs a single
>> share, my proposal was to use `getCpuShares` as a multiplier for
>> `periodLength` above.
>> Is there a good reason `getCpuQuota` is a better alternative?
>
> Hi Argha, thanks a lot for your suggestion. I think both "quota" and "share"
> are worth considering. Let us look into the implementation of
> `CgroupSubsystem::active_processor_count()` in OpenJDK HotSpot
> (https://github.com/openjdk/jdk/blob/master/src/hotspot/os/linux/cgroupSubsystem_linux.cpp).
Thanks for linking that. It sounds reasonable to me to prefer `quota` in that
case.
-------------
PR: https://git.openjdk.java.net/jdk/pull/3656
