java-8 cgroup without UseCGroupMemoryLimitForHeap

Question

This continues kind of this question

I am making the same steps as there, but this time, I am dropping UseCGroupMemoryLimitForHeap:

java -XX:InitialRAMPercentage=50.0 -XX:MaxRAMPercentage=50.0 -XX:+AlwaysPreTouch Dummy &

And I am trying to inspect it a little:

jcmd 279 VM.flags

Among other things, I see :

-XX:InitialHeapSize=2063597568
-XX:InitialRAMPercentage=50.000000
-XX:MaxRAMPercentage=50.000000
-XX:MaxHeapSize=2063597568

From a recommendation from this answer from Pangin, he says that:

-XX:InitialRAMPercentage is used to calculate initial heap size when InitialHeapSize / -Xms is not set.

and :

... both -XX:MaxRAMPercentage and -XX:MinRAMPercentage are used to calculate maximum heap size when MaxHeapSize / -Xmx is not set

My understanding that I should not set InitialHeapSize/Xms and MaxHeapSize/Xmx and I don't, but they are set for me.

I thought that I could say -XX:InitialHeapSize=0 and -XX:MaxHeapSize=0, but of course this does not work and the VM does not start.

The last point is that :

top -o %MEM

shows a 2GB of resident memory for the java process, so yeah, both InitialRAMPercentage/MaxRAMPercentage seems to be pointless?

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The interesting thing here is that if I run this in jdk-17:

 java -XX:InitialRAMPercentage=50.0 -XX:MaxRAMPercentage=50.0 -XX:+AlwaysPreTouch Dummy &

then top -o %MEM shows 1GB, exactly like I want it to be.