RFR(XXS): 8027454: Do not traverse string table during G1 remark when treating them as strong roots during initial mark

[Thomas Schatzl]

Hi all,

  could I have some reviews for the following tiny change?

It disables string table unlink in the G1 remark pause. This is not
required as G1 initial mark treats them as strong roots always.

This needs to be changed again as soon as class unloading during
concurrent mark is implemented, but for now it gives a performance boost
about 10-15% of the remark pause across many applications.

It is based on the recently posted RFR for JDK-8027476.

Webrev:
http://cr.openjdk.java.net/~tschatzl/8027454/webrev/

bugs.sun.com:
https://bugs.openjdk.java.net/browse/JDK-8027454

Testing:
jprt, FMW apps, specjbb2005, specjbb2013, dacapo, and lots
of other testing in the recent months

Thanks,
  Thomas


Thanks,
  Thomas