required = mr.reservedPages() - mr.committedPages(); if (mr == nurseryMR || mr == matureMR) required = required<<1;
  public boolean poll(boolean mustCollect, MemoryResource mr)     throws VM_PragmaLogicallyUninterruptible {    if (gcInProgress) return false;    if (mustCollect || getPagesReserved() > getTotalPages()) {      if (VM.VerifyAssertions)	VM._assert(mr != metaDataMR);      fullHeapGC = mustCollect || fullHeapGC;      VM_Interface.triggerCollection();      return true;    }    return false;  }