src/share/vm/gc_implementation/parallelScavenge/psAdaptiveSizePolicy.cpp

rev 5803 : 8028391: Make the Min/MaxHeapFreeRatio flags manageable
Summary: Made the flags Min- and MaxHeapFreeRatio manageable, and implemented support for these flags in ParallalGC.
Reviewed-by: sla, mgerdin, brutisso

*** 21,30 ****
--- 21,31 ----
   * questions.
   *
   */
  
  #include "precompiled.hpp"
+ #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
  #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
  #include "gc_implementation/parallelScavenge/psGCAdaptivePolicyCounters.hpp"
  #include "gc_implementation/parallelScavenge/psScavenge.hpp"
  #include "gc_implementation/shared/gcPolicyCounters.hpp"
  #include "gc_interface/gcCause.hpp"
*** 74,83 ****
--- 75,116 ----
    _major_timer.start();
  
    _old_gen_policy_is_ready = false;
  }
  
+ size_t PSAdaptiveSizePolicy::calculate_free_based_on_live(size_t live, uintx ratio_as_percentage) {
+   // We want to calculate how much free memory there can be based on the
+   // amount of live data currently in the old gen. Using the formula:
+   // ratio * (free + live) = free
+   // Some equation solving later we get:
+   // free = (live * ratio) / (1 - ratio)
+ 
+   const double ratio = ratio_as_percentage / 100.0;
+   const double ratio_inverse = 1.0 - ratio;
+   const double tmp = live * ratio;
+   size_t free = (size_t)(tmp / ratio_inverse);
+ 
+   return free;
+ }
+ 
+ size_t PSAdaptiveSizePolicy::calculated_old_free_size_in_bytes() const {
+   size_t free_size = (size_t)(_promo_size + avg_promoted()->padded_average());
+   size_t live = ParallelScavengeHeap::heap()->old_gen()->used_in_bytes();
+ 
+   if (MinHeapFreeRatio != 0) {
+     size_t min_free = calculate_free_based_on_live(live, MinHeapFreeRatio);
+     free_size = MAX2(free_size, min_free);
+   }
+ 
+   if (MaxHeapFreeRatio != 100) {
+     size_t max_free = calculate_free_based_on_live(live, MaxHeapFreeRatio);
+     free_size = MIN2(max_free, free_size);
+   }
+ 
+   return free_size;
+ }
+ 
  void PSAdaptiveSizePolicy::major_collection_begin() {
    // Update the interval time
    _major_timer.stop();
    // Save most recent collection time
    _latest_major_mutator_interval_seconds = _major_timer.seconds();
*** 1290,1294 ****
--- 1323,1342 ----
  
    return AdaptiveSizePolicy::print_adaptive_size_policy_on(
                            st,
                            PSScavenge::tenuring_threshold());
  }
+ 
+ #ifndef PRODUCT
+ 
+ void TestOldFreeSpaceCalculation_test() {
+   assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 20) == 25, "Calculation of free memory failed");
+   assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 50) == 100, "Calculation of free memory failed");
+   assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 60) == 150, "Calculation of free memory failed");
+   assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 75) == 300, "Calculation of free memory failed");
+   assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 20) == 100, "Calculation of free memory failed");
+   assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 50) == 400, "Calculation of free memory failed");
+   assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 60) == 600, "Calculation of free memory failed");
+   assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 75) == 1200, "Calculation of free memory failed");
+ }
+ 
+ #endif /* !PRODUCT */