diff -r 230882b8173e -r f67f588ebf15 src/hotspot/share/gc/shared/collectedHeap.hpp
--- a/src/hotspot/share/gc/shared/collectedHeap.hpp	Thu Apr 26 19:32:01 2018 +0200
+++ b/src/hotspot/share/gc/shared/collectedHeap.hpp	Thu May 03 09:43:47 2018 +0200
@@ -126,7 +126,13 @@
   CollectedHeap();
 
   // Create a new tlab. All TLAB allocations must go through this.
-  virtual HeapWord* allocate_new_tlab(size_t size);
+  // To allow more flexible TLAB allocations min_size specifies
+  // the minimum size needed, while requested_size is the requested
+  // size based on ergonomics. The actually allocated size will be
+  // returned in actual_size.
+  virtual HeapWord* allocate_new_tlab(size_t min_size,
+                                      size_t requested_size,
+                                      size_t* actual_size);
 
   // Accumulate statistics on all tlabs.
   virtual void accumulate_statistics_all_tlabs();