[MOD-11237] Block Size Boundary Oscillation Benchmark

[meiravgri]

Purpose

This PR introduces a new benchmark UpdateAtBlockSize that reproduces the allocation/deallocation oscillation issue that occurs when repeatedly updating vectors at block size boundaries. This benchmark demonstrates the performance impact of the problem addressed in PR #753:

Problem Being Benchmarked

The benchmark reproduces a scenario where:

• Index size is set to blockSize + 1 (one element past a block boundary)
• Repeatedly deleting and re-adding the same vector triggers constant grow-shrink cycles
• This causes frequent allocation/deallocation of large containers (hash tables, metadata vectors)
• Results in significant performance overhead due to memory management oscillations

Implementation Details

Test Coverage: Added to both single and multi-index benchmark suites:

• bm_basics_single_fp32.cpp - Single-index scenarios
• bm_basics_multi_fp32.cpp - Multi-index scenarios
• Covers BruteForce, HNSW, and Tiered HNSW algorithms

Additional Changes

Counter Improvements: Enhanced memory-related counters across all benchmarks:

• Applied consistent benchmark::Counter::OneK::kIs1024 formatting for memory counters to display values in KB units (dividing by 1024 multipliers)

Expected Results

• Before PR [MOD-10559] Decouple the shrinking and growing logic of large containers in Flat and HNSW #753: High allocation overhead due to capacity oscillating between index_cap and index_cap - block_size on each update cycle
• After PR [MOD-10559] Decouple the shrinking and growing logic of large containers in Flat and HNSW #753: Stable performance with minimal allocations due to conservative resize strategy preventing unnecessary shrinking operations

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.85%. Comparing base (d60ab7c) to head (bb86b2f).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #768      +/-   ##
==========================================
+ Coverage   96.82%   96.85%   +0.02%     
==========================================
  Files         122      122              
  Lines        7496     7496              
==========================================
+ Hits         7258     7260       +2     
+ Misses        238      236       -2     

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[alonre24]

nice!

[github-actions]

Backport failed for 0.6, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin 0.6
git worktree add -d .worktree/backport-768-to-0.6 origin/0.6
cd .worktree/backport-768-to-0.6
git switch --create backport-768-to-0.6
git cherry-pick -x fd08b5521ab3b3bdcbe58b6f919ea46a704ecf44

[github-actions]

Backport failed for 0.7, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin 0.7
git worktree add -d .worktree/backport-768-to-0.7 origin/0.7
cd .worktree/backport-768-to-0.7
git switch --create backport-768-to-0.7
git cherry-pick -x fd08b5521ab3b3bdcbe58b6f919ea46a704ecf44

[github-actions]

Backport failed for 0.8, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin 0.8
git worktree add -d .worktree/backport-768-to-0.8 origin/0.8
cd .worktree/backport-768-to-0.8
git switch --create backport-768-to-0.8
git cherry-pick -x fd08b5521ab3b3bdcbe58b6f919ea46a704ecf44

[github-actions]

Backport failed for 8.0, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin 8.0
git worktree add -d .worktree/backport-768-to-8.0 origin/8.0
cd .worktree/backport-768-to-8.0
git switch --create backport-768-to-8.0
git cherry-pick -x fd08b5521ab3b3bdcbe58b6f919ea46a704ecf44

[github-actions]

Successfully created backport PR for 8.2:

• [8.2] [MOD-11237] Block Size Boundary Oscillation Benchmark #769