8u171/8u172 b07 Footprint3-Jetty-* footprint regression

In b07 of both 8u171 and 8u172, two measures are showing a footprint regression:
    Footprint3-Jetty-G1/Linux-x86 approx -10% (~ 7.7MB)
    Footprint3-Jetty-ParGC/Win-x86 approx -7% to -10% (~ 6.3 to 8.5MB)
    
The regression holds into 8u172-b08.

We DO NOT see the regression in either 10.0.1 b6 or b7.

The regression reproduces in:
• Triage (ie, re-run on the same machine)
• Re-triage (ie, run on a different machine)

JVMswap results indicate the cause is in the JDK (not the JVM).