diff -r 2251ba078bec -r eb7ce841ccec src/share/vm/memory/threadLocalAllocBuffer.cpp
--- a/src/share/vm/memory/threadLocalAllocBuffer.cpp	Sat Oct 24 16:18:50 2020 +0800
+++ b/src/share/vm/memory/threadLocalAllocBuffer.cpp	Sat Oct 24 16:43:47 2020 +0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -88,7 +88,8 @@
       // The result can be larger than 1.0 due to direct to old allocations.
       // These allocations should ideally not be counted but since it is not possible
       // to filter them out here we just cap the fraction to be at most 1.0.
-      double alloc_frac = MIN2(1.0, (double) allocated_since_last_gc / used);
+      // Keep alloc_frac as float and not double to avoid the double to float conversion
+      float alloc_frac = MIN2(1.0f, allocated_since_last_gc / (float) used);
       _allocation_fraction.sample(alloc_frac);
     }
     global_stats()->update_allocating_threads();
@@ -205,7 +206,8 @@
   // this thread is redone in startup_initialization below.
   if (Universe::heap() != NULL) {
     size_t capacity   = Universe::heap()->tlab_capacity(myThread()) / HeapWordSize;
-    double alloc_frac = desired_size() * target_refills() / (double) capacity;
+    // Keep alloc_frac as float and not double to avoid the double to float conversion
+    float alloc_frac = desired_size() * target_refills() / (float) capacity;
     _allocation_fraction.sample(alloc_frac);
   }