ZGC heap size and RSS counters

[Aleksey Shipilev]

Hi there,

I'm trying ZGC on trivial workloads, and I have a question about footprint. The workload runs with
-Xms16g -Xms16g, but the RSS figures are at least 3x larger:

VmPeak:	18256721392 kB
VmSize:	18256721392 kB
VmLck:	       0 kB
VmPin:	       0 kB
VmHWM:	50729036 kB
VmRSS:	50729036 kB
RssAnon:	  369700 kB
RssFile:	   27688 kB
RssShmem:	50331648 kB

Is this because ZGC maps the same physical space with multiple virtual mappings? Or is it a bug?

Thanks,
-Aleksey