[MOD-11237] Block Size Boundary Oscillation Benchmark

tests/benchmark/bm_common.h

@@ -70,7 +70,9 @@ void BM_VecSimCommon<index_type_t>::Memory(benchmark::State &st, IndexTypeIndex
     for (auto _ : st) {
         // Do nothing...
     }
-    st.counters["memory"] = (double)VecSimIndex_StatsInfo(index).memory;
+    st.counters["memory"] =
+        benchmark::Counter((double)VecSimIndex_StatsInfo(index).memory,
+                           benchmark::Counter::kDefaults, benchmark::Counter::OneK::kIs1024);
 }
 
 // TopK search BM

tests/benchmark/bm_vecsim_basics.h

@@ -42,6 +42,14 @@ class BM_VecSimBasics : public BM_VecSimCommon<index_type_t> {
     static void Range_BF(benchmark::State &st);
     static void Range_HNSW(benchmark::State &st);
 
+    // Reproduces allocation/deallocation oscillation issue at block size boundaries.
+    // Sets up index at blockSize+1 capacity, then repeatedly deletes and re-adds the same vector,
+    // triggering constant grow-shrink cycles.
+    // This behavior was fixed by PR #753 with a conservative resize strategy that only
+    // shrinks containers when there are 2+ free blocks, preventing oscillation cycles.
+    // Expected: High allocation overhead before fix, stable performance after fix.
+    static void UpdateAtBlockSize(benchmark::State &st);
+
 private:
     // Vectors of vector to store deleted labels' data.
     using LabelData = std::vector<std::vector<data_t>>;
@@ -76,7 +84,9 @@ void BM_VecSimBasics<index_type_t>::AddLabel(benchmark::State &st) {
     // For tiered index, wait for all threads to finish indexing
     BM_VecSimGeneral::mock_thread_pool->thread_pool_wait();
 
-    st.counters["memory_per_vector"] = (double)memory_delta / (double)added_vec_count;
+    st.counters["memory_per_vector"] =
+        benchmark::Counter((double)memory_delta / (double)added_vec_count,
+                           benchmark::Counter::kDefaults, benchmark::Counter::OneK::kIs1024);
     st.counters["vectors_per_label"] = vec_per_label;
 
     assert(VecSimIndex_IndexSize(index) == N_VECTORS + added_vec_count);
@@ -123,7 +133,9 @@ void BM_VecSimBasics<index_type_t>::AddLabel_AsyncIngest(benchmark::State &st) {
     }
 
     size_t memory_delta = index->getAllocationSize() - memory_before;
-    st.counters["memory_per_vector"] = (double)memory_delta / (double)added_vec_count;
+    st.counters["memory_per_vector"] =
+        benchmark::Counter((double)memory_delta / (double)added_vec_count,
+                           benchmark::Counter::kDefaults, benchmark::Counter::OneK::kIs1024);
     st.counters["vectors_per_label"] = vec_per_label;
     st.counters["num_threads"] = BM_VecSimGeneral::mock_thread_pool->thread_pool_size;
 
@@ -173,7 +185,9 @@ void BM_VecSimBasics<index_type_t>::DeleteLabel(algo_t *index, benchmark::State
     if (VecSimIndex_BasicInfo(index).algo == VecSimAlgo_TIERED) {
         dynamic_cast<TieredHNSWIndex<data_t, dist_t> *>(index)->executeReadySwapJobs();
     }
-    st.counters["memory_per_vector"] = memory_delta / (double)removed_vectors_count;
+    st.counters["memory_per_vector"] =
+        benchmark::Counter((double)memory_delta / (double)removed_vectors_count,
+                           benchmark::Counter::kDefaults, benchmark::Counter::OneK::kIs1024);
 
     // Restore index state.
     // For each label in removed_labels_data
@@ -223,7 +237,10 @@ void BM_VecSimBasics<index_type_t>::DeleteLabel_AsyncRepair(benchmark::State &st
     // Avg. memory delta per vector equals the total memory delta divided by the number
     // of deleted vectors.
     double memory_delta = tiered_index->getAllocationSize() - memory_before;
-    st.counters["memory_per_vector"] = memory_delta / (double)removed_vectors_count;
+
+    st.counters["memory_per_vector"] =
+        benchmark::Counter((double)memory_delta / (double)removed_vectors_count,
+                           benchmark::Counter::kDefaults, benchmark::Counter::OneK::kIs1024);
     st.counters["num_threads"] = (double)BM_VecSimGeneral::mock_thread_pool->thread_pool_size;
     st.counters["num_zombies"] = tiered_index->idToSwapJob.size();
 
@@ -294,6 +311,69 @@ void BM_VecSimBasics<index_type_t>::Range_HNSW(benchmark::State &st) {
     st.counters["Recall"] = (float)total_res / total_res_bf;
 }
 
+template <typename index_type_t>
+void BM_VecSimBasics<index_type_t>::UpdateAtBlockSize(benchmark::State &st) {
+    auto index = GET_INDEX(st.range(0));
+    size_t initial_index_size = VecSimIndex_IndexSize(index);
+    // Calculate vectors needed to reach next block boundary
+    size_t vecs_to_blocksize =
+        BM_VecSimGeneral::block_size - (initial_index_size % BM_VecSimGeneral::block_size);
+    assert(vecs_to_blocksize < BM_VecSimGeneral::block_size);
+    labelType initial_label_count = index->indexLabelCount();
+    labelType curr_label = initial_label_count;
+
+    // Set up index at blockSize+1 to trigger oscillation issue
+    // Make sure we have enough queries to add a new label.
+    assert(N_QUERIES > BM_VecSimGeneral::block_size);
+    size_t overhead = 1;
+    size_t added_vec_count = vecs_to_blocksize + overhead;
+    for (size_t i = 0; i < added_vec_count; ++i) {
+        VecSimIndex_AddVector(index, QUERIES[added_vec_count % N_QUERIES].data(), curr_label++);
+    }
+    // For tiered index, wait for all threads to finish indexing
+    BM_VecSimGeneral::mock_thread_pool->thread_pool_wait();
+    assert(VecSimIndex_IndexSize(index) % BM_VecSimGeneral::block_size == overhead);
+    assert(VecSimIndex_IndexSize(index) == N_VECTORS + added_vec_count);
+
+    std::cout << "Added " << added_vec_count << " vectors to reach block size boundary."
+              << std::endl;
+    std::cout << "Index size is now " << VecSimIndex_IndexSize(index) << std::endl;
+    std::cout << "Last label is " << curr_label - 1 << std::endl;
+
+    // Benchmark loop: repeatedly delete/add same vector to trigger grow-shrink cycles
+    labelType label_to_update = curr_label - 1;
+    size_t index_cap = index->indexCapacity();
+    for (auto _ : st) {
+        // Remove the vector directly from hnsw
+        size_t ret = VecSimIndex_DeleteVector(
+            GET_INDEX(st.range(0) == INDEX_TIERED_HNSW ? INDEX_HNSW : st.range(0)),
+            label_to_update);
+        assert(ret == 1);
+        assert(index->indexCapacity() == index_cap - BM_VecSimGeneral::block_size);
+        // Capacity should shrink by one block after deletion
+        ret = VecSimIndex_AddVector(index, QUERIES[(added_vec_count - 1) % N_QUERIES].data(),
+                                    label_to_update);
+        assert(ret == 1);
+        BM_VecSimGeneral::mock_thread_pool->thread_pool_wait();
+        assert(VecSimIndex_IndexSize(
+                   GET_INDEX(st.range(0) == INDEX_TIERED_HNSW ? INDEX_HNSW : st.range(0))) ==
+               N_VECTORS + added_vec_count);
+        // Capacity should grow back to original size after addition
+        assert(index->indexCapacity() == index_cap);
+    }
+    assert(VecSimIndex_IndexSize(index) == N_VECTORS + added_vec_count);
+
+    // Clean-up all the new vectors to restore the index size to its original value.
+
+    size_t new_label_count = index->indexLabelCount();
+    for (size_t label = initial_label_count; label < new_label_count; label++) {
+        // If index is tiered HNSW, remove directly from the underline HNSW.
+        VecSimIndex_DeleteVector(
+            GET_INDEX(st.range(0) == INDEX_TIERED_HNSW ? INDEX_HNSW : st.range(0)), label);
+    }
+    assert(VecSimIndex_IndexSize(index) == N_VECTORS);
+}
+
 #define UNIT_AND_ITERATIONS Unit(benchmark::kMillisecond)->Iterations(BM_VecSimGeneral::block_size)
 
 // These macros are used to make sure the expansion of other macros happens when needed
@@ -345,3 +425,8 @@ void BM_VecSimBasics<index_type_t>::Range_HNSW(benchmark::State &st) {
     }
 #define REGISTER_DeleteLabel(BM_FUNC)                                                              \
     BENCHMARK_REGISTER_F(BM_VecSimBasics, BM_FUNC)->UNIT_AND_ITERATIONS
+
+#define REGISTER_UpdateAtBlockSize(BM_FUNC, VecSimAlgo)                                            \
+    BENCHMARK_REGISTER_F(BM_VecSimBasics, BM_FUNC)                                                 \
+        ->UNIT_AND_ITERATIONS->Arg(VecSimAlgo)                                                     \
+        ->ArgName(#VecSimAlgo)

tests/benchmark/run_files/bm_basics_multi_fp32.cpp

@@ -35,4 +35,12 @@ DEFINE_DELETE_LABEL(BM_FUNC_NAME(DeleteLabel, Tiered), fp32_index_t, TieredHNSWI
                     INDEX_TIERED_HNSW)
 #include "benchmark/bm_initialization/bm_basics_initialize_fp32.h"
 
+// Test oscillations at block size boundaries.
+BENCHMARK_TEMPLATE_DEFINE_F(BM_VecSimBasics, CONCAT_WITH_UNDERSCORE_ARCH(UpdateAtBlockSize, Multi),
+                            fp32_index_t)
+(benchmark::State &st) { UpdateAtBlockSize(st); }
+REGISTER_UpdateAtBlockSize(CONCAT_WITH_UNDERSCORE_ARCH(UpdateAtBlockSize, Multi), INDEX_BF);
+REGISTER_UpdateAtBlockSize(CONCAT_WITH_UNDERSCORE_ARCH(UpdateAtBlockSize, Multi), INDEX_HNSW);
+REGISTER_UpdateAtBlockSize(CONCAT_WITH_UNDERSCORE_ARCH(UpdateAtBlockSize, Multi),
+                           INDEX_TIERED_HNSW);
 BENCHMARK_MAIN();

tests/benchmark/run_files/bm_basics_single_fp32.cpp

@@ -31,5 +31,14 @@ DEFINE_DELETE_LABEL(BM_FUNC_NAME(DeleteLabel, HNSW), fp32_index_t, HNSWIndex_Sin
                     INDEX_HNSW)
 DEFINE_DELETE_LABEL(BM_FUNC_NAME(DeleteLabel, Tiered), fp32_index_t, TieredHNSWIndex, float, float,
                     INDEX_TIERED_HNSW)
+
+// Test Oscilations
+BENCHMARK_TEMPLATE_DEFINE_F(BM_VecSimBasics, CONCAT_WITH_UNDERSCORE_ARCH(UpdateAtBlockSize, Single),
+                            fp32_index_t)
+(benchmark::State &st) { UpdateAtBlockSize(st); }
+REGISTER_UpdateAtBlockSize(CONCAT_WITH_UNDERSCORE_ARCH(UpdateAtBlockSize, Single), INDEX_BF);
+REGISTER_UpdateAtBlockSize(CONCAT_WITH_UNDERSCORE_ARCH(UpdateAtBlockSize, Single), INDEX_HNSW);
+REGISTER_UpdateAtBlockSize(CONCAT_WITH_UNDERSCORE_ARCH(UpdateAtBlockSize, Single),
+                           INDEX_TIERED_HNSW);
 #include "benchmark/bm_initialization/bm_basics_initialize_fp32.h"
 BENCHMARK_MAIN();