RFR(M): 8243392: Remodel CDS/Metaspace storage reservation

[coleen.phillimore at oracle.com]

Hi I've reviewed this change and it looks good to me.  Some comments on 
the thread.

On 5/13/20 1:49 AM, Thomas Stüfe wrote:
> (trimmed down the list of recipients)
>
>
>> If you have a running foreground JVM in your Linux terminal, you can type
>> "Ctrl-\" and see this. E.g.,
>>
>>
> Oh, backslash. I tried backspace. My error.
>
>
>> $ java -cp . SleepForever
>> <...>
>> Heap
>>   garbage-first heap   total 1048576K, used 824K [0x0000000412000000,
>> 0x0000000800000000)
>>    region size 8192K, 1 young (8192K), 0 survivors (0K)
>>   Metaspace       used 143K, capacity 4486K, committed 4864K, reserved
>> 1056768K
>>    class space    used 6K, capacity 386K, committed 512K, reserved 1048576K
>>
>>
> Note that this output is not from NMT and so the numbers are not affected
> by the NMT bug. Only the jcmd VM.native_memory output is affected.

This info is printed by VM_PrintThreads operation (also kill -3).
>
>> Actually I see that the current output is not correct -- class space
>> doesn't include the CDS sizes :-(
>>
>>
> I think I'like to keep CDS and CCS separate in the output for a number of
> reasons. One is that CCSSize only applies to CCS. But more important, CDS
> can be shared and CCS not.
>
> But we may print out CDS too in this output, in a separate line.

Yes, this would be good but I think the places that print the heap 
should also print CDS, and not add CDS printing to Metaspace::print_on() 
where the metaspace printing comes from.

Coleen
>
> Cheers, Thomas