rust_leaf_bench/

Rust Leaf Page Smoke Benchmark

This is a small TreeDB leaf-page experiment. It ports the benchmark shapes from TreeDB/node into standalone Go, C, and Rust smoke binaries so we can separate the production TreeDB Go path from narrower matched-algorithm comparisons.

The goal is smoke-test signal, not a production Rust dependency.

What It Covers

• Builder smoke cases matching:
  • BenchmarkAddLeafEntryWithPrefix_NoPrefix
  • BenchmarkAddLeafEntryWithPrefix_PrefixHeavy
  • BenchmarkAddLeafEntryWithPrefix_PrefixLight
• Search smoke cases matching:
  • BenchmarkSearchLeaf_Columnar_FixedBE8
  • BenchmarkSearchLeaf_Columnar_Variable16
  • BenchmarkSearchLeaf_PrefixV2
  • BenchmarkSearchLeaf_ColumnarPrefixV2

The standalone Go, C, and Rust code all mirror TreeDB constants such as 4 KiB pages, 16-byte page headers, 2-byte directory entries, 16-entry prefix restart blocks, 16-byte value pointers, and the same key/value sizes used by the Go microbenchmarks.

Run

From the repo root:

experiments/rust_leaf_bench/run_leaf_smoke.sh

The script runs the production Go microbenchmarks, runs the matched standalone Go smoke binary, compiles/runs the matched C smoke binary, runs the Rust release binary, and prints a compact comparison table. It also writes raw output files under /tmp.

Useful knobs:

BENCHTIME=2s COUNT=5 experiments/rust_leaf_bench/run_leaf_smoke.sh
LEAF_BUILD_ITERS=2000000 LEAF_SEARCH_ITERS=5000000 experiments/rust_leaf_bench/run_leaf_smoke.sh
CC=clang CFLAGS="-O3 -std=c11 -Wall -Wextra" experiments/rust_leaf_bench/run_leaf_smoke.sh

Profile Go And Rust

To regenerate matched Go/Rust perf profiles without the C row:

experiments/rust_leaf_bench/profile_leaf_go_rust.sh

The profiler builds the standalone matched Go binary, builds Rust release with frame pointers and the profile-attribution feature, then records one perf profile per selected case. It writes a Markdown summary plus raw perf.data, perf.report.txt, and stdout files under /tmp.

Useful knobs:

CASES="search/prefix_v2 search/columnar_prefix_v2" experiments/rust_leaf_bench/profile_leaf_go_rust.sh
LEAF_SEARCH_ITERS=50000000 PERF_FREQ=1997 experiments/rust_leaf_bench/profile_leaf_go_rust.sh
GO_PROFILE_GOGC=100 experiments/rust_leaf_bench/profile_leaf_go_rust.sh
OUT_DIR=/tmp/leaf_profiles experiments/rust_leaf_bench/profile_leaf_go_rust.sh

There is also a Go-only diagnostic probe for fixed-width columnar keys:

LEAF_CASE=search/columnar_fixed_be8_direct LEAF_SEARCH_ITERS=20000000 go run ./experiments/rust_leaf_bench/matched_go

That probe bypasses the generic columnarKeyAt slice-return path and compares the 8-byte key in place. It is intentionally not part of the default apples-to-apples table.

Caveats

• The matched Go, C, and Rust paths are intentionally standalone and do not FFI into TreeDB.
• The benchmark shapes and constants match the Go benches, but the standalone fixture generator is deterministic rather than a byte-for-byte clone of Go math/rand.
• The most useful reads are c/mgo, r/mgo, and r/c, because they control for the narrower smoke implementation better than comparing C or Rust directly to production Go.
• The profile script uses a Rust-only profile-attribution feature to prevent selected hot functions from being inlined away in perf reports. Use run_leaf_smoke.sh for throughput numbers.
• The profile script defaults Go to GOGC=off to keep setup-time garbage collection out of the smoke profiles. Set GO_PROFILE_GOGC=100 to profile with Go's normal collector setting.
• Treat small deltas as noise. This script is for quickly spotting large, interesting differences worth investigating in the Go implementation.