On 2 tests that exercise the vm_map vigoriously, these are the runtimes and dc-misses with and without the change in place:
After:
Test 1 Test 2
seconds dc-misses seconds dc-misses
17.560116 722565243 16.622748 693637295
17.639686 775200254 16.802701 712008743
17.649738 748864923 16.798993 711638822
17.638408 750120061 16.659986 681725674
17.663416 715930237 16.733286 701438778
Before:
Test 1 Test 2
seconds dc-misses seconds dc-misses
18.448940 697424367 17.487485 680852142
18.520613 700154192 17.488678 670644687
18.369913 696744015 17.553468 668572905
18.412856 704237817 17.457770 664390472
18.513684 700244077 17.480940 664748569