RFR(L): 8233705: Let artifact iteration running time be a function of incrementally tagged artifacts

[Markus Gronlund]

Greetings,

Please review the following enhancement:

Enh. / bug: https://bugs.openjdk.java.net/browse/JDK-8233705
Webrev: http://cr.openjdk.java.net/~mgronlun/8233705/webrev/ 
Testing: jdk_jfr, stress tests

This change build on top of the change set for JDK-8242088, and the webrev linked above is a diff against the JDK-8242088 webrev:

Enh / bug: https://bugs.openjdk.java.net/browse/JDK-8242088 
Webrev: http://cr.openjdk.java.net/~mgronlun/8242088/webrev/ 

Thanks
Markus