os/Allocator_tests: Add dedicated test for fragmentation score

Add special tests for fragmentation score. Give broad range,
but require them to follow certain behavours.

Signed-off-by: Adam Kupczyk <akupczyk@ibm.com>
(cherry picked from commit 5b54a13354fbea5d59e8d9ab6015eff7d6d05954)

diff --git a/src/test/objectstore/Allocator_test.cc b/src/test/objectstore/Allocator_test.cc
index b006500153c6e389a3d1c617cadfa2fd180f6008..186063aa7f799b8fdb396f7d6c3e31315bc96608 100644 (file)
--- a/src/test/objectstore/Allocator_test.cc
+++ b/src/test/objectstore/Allocator_test.cc
@@ -301,7 +301,6 @@ TEST_P(AllocTest, test_alloc_fragmentation)
     alloc->release(release_set);
   }
   EXPECT_EQ(1.0, alloc->get_fragmentation());
-  EXPECT_EQ(66u, uint64_t(alloc->get_fragmentation_score() * 100));
 
   for (size_t i = 1; i < allocated.size() / 2; i += 2)
   {
@@ -316,7 +315,6 @@ TEST_P(AllocTest, test_alloc_fragmentation)
     // fragmentation approx = 257 intervals / 768 max intervals
     EXPECT_EQ(33u, uint64_t(alloc->get_fragmentation() * 100));
   }
-  EXPECT_EQ(27u, uint64_t(alloc->get_fragmentation_score() * 100));
 
   for (size_t i = allocated.size() / 2 + 1; i < allocated.size(); i += 2)
   {
@@ -329,11 +327,84 @@ TEST_P(AllocTest, test_alloc_fragmentation)
   // Hence leaving just two 
   // digits after decimal point due to this.
   EXPECT_EQ(0u, uint64_t(alloc->get_fragmentation() * 100));
-  if (bitmap_alloc) {
-    EXPECT_EQ(0u, uint64_t(alloc->get_fragmentation_score() * 100));
-  } else {
-    EXPECT_EQ(11u, uint64_t(alloc->get_fragmentation_score() * 100));
+}
+
+TEST_P(AllocTest, test_fragmentation_score_0)
+{
+  uint64_t capacity = 16LL * 1024 * 1024 * 1024; //16 GB, very small
+  uint64_t alloc_unit = 4096;
+
+  init_alloc(capacity, alloc_unit);
+  alloc->init_add_free(0, capacity);
+  EXPECT_EQ(0, alloc->get_fragmentation_score());
+
+  // alloc every 100M, should get very small score
+  for (uint64_t pos = 0; pos < capacity; pos +=  100 * 1024 * 1024) {
+    alloc->init_rm_free(pos, alloc_unit);
+  }
+  EXPECT_LT(alloc->get_fragmentation_score(), 0.0001); // frag < 0.01%
+  for (uint64_t pos = 0; pos < capacity; pos +=  100 * 1024 * 1024) {
+    // put back
+    alloc->init_add_free(pos, alloc_unit);
+  }
+
+  // 10% space is trashed, rest is free, small score
+  for (uint64_t pos = 0; pos < capacity / 10; pos +=  3 * alloc_unit) {
+    alloc->init_rm_free(pos, alloc_unit);
+  }
+  EXPECT_LT(0.01, alloc->get_fragmentation_score()); // 1% < frag < 10%
+  EXPECT_LT(alloc->get_fragmentation_score(), 0.1);
+}
+
+TEST_P(AllocTest, test_fragmentation_score_some)
+{
+  uint64_t capacity = 1024 * 1024 * 1024; //1 GB, very small
+  uint64_t alloc_unit = 4096;
+
+  init_alloc(capacity, alloc_unit);
+  alloc->init_add_free(0, capacity);
+  // half (in 16 chunks) is completely free,
+  // other half completely fragmented, expect less than 50% fragmentation score
+  for (uint64_t chunk = 0; chunk < capacity; chunk += capacity / 16) {
+    for (uint64_t pos = 0; pos < capacity / 32; pos += alloc_unit * 3) {
+      alloc->init_rm_free(chunk + pos, alloc_unit);
+    }
+  }
+  EXPECT_LT(alloc->get_fragmentation_score(), 0.5); // f < 50%
+
+  init_alloc(capacity, alloc_unit);
+  alloc->init_add_free(0, capacity);
+  // half (in 16 chunks) is completely full,
+  // other half completely fragmented, expect really high fragmentation score
+  for (uint64_t chunk = 0; chunk < capacity; chunk += capacity / 16) {
+    alloc->init_rm_free(chunk + capacity / 32, capacity / 32);
+    for (uint64_t pos = 0; pos < capacity / 32; pos += alloc_unit * 3) {
+      alloc->init_rm_free(chunk + pos, alloc_unit);
+    }
+  }
+  EXPECT_LT(0.9, alloc->get_fragmentation_score()); // 50% < f
+}
+
+TEST_P(AllocTest, test_fragmentation_score_1)
+{
+  uint64_t capacity = 1024 * 1024 * 1024; //1 GB, very small
+  uint64_t alloc_unit = 4096;
+
+  init_alloc(capacity, alloc_unit);
+  alloc->init_add_free(0, capacity);
+  // alloc every second AU, max fragmentation
+  for (uint64_t pos = 0; pos < capacity; pos += alloc_unit * 2) {
+    alloc->init_rm_free(pos, alloc_unit);
+  }
+  EXPECT_LT(0.99, alloc->get_fragmentation_score()); // 99% < f
+
+  init_alloc(capacity, alloc_unit);
+  alloc->init_add_free(0, capacity);
+  // 1 allocated, 4 empty; expect very high score
+  for (uint64_t pos = 0; pos < capacity; pos += alloc_unit * 5) {
+    alloc->init_rm_free(pos, alloc_unit);
   }
+  EXPECT_LT(0.90, alloc->get_fragmentation_score()); // 90% < f
 }
 
 TEST_P(AllocTest, test_dump_fragmentation_score)