dumac

My blog posts:

• Maybe the Fastest Disk Usage Program on macOS
• Optimizing My Disk Usage Program

A very fast du -sh clone for macOS. Maybe the fastest.

dumac calculates the size of a given directory.

It's a parallelized version of du -sh and uses highly efficient macOS syscalls (getattrlistbulk – avaliable since Mac OS X 10.10).

dumac /tmp/
11.5K   /tmp/

Benchmarks

It has been benchmarked (and beats) against most of the tools that come up when you search "disk usage CLI for macOS" but the fairest comparisons are du and diskus because they don't generate other output.

My benchmark is a directory with 12 levels, 100 small files per level, with a branching factor of two — 4095 directories, 409500 files.

It's ran with a warm disk cache as I found that warm disk cache performance strongly correlates with cold disk cache performance on macOS with modern Apple hardware.

hyperfine --warmup 3 --min-runs 5 'du -sh temp/deep' 'diskus temp/deep' './target/release/dumac temp/deep'
Benchmark 1: du -sh temp/deep
  Time (mean ± σ):      3.186 s ±  0.198 s    [User: 0.040 s, System: 1.391 s]
  Range (min … max):    2.851 s …  3.367 s    5 runs

Benchmark 2: diskus temp/deep
  Time (mean ± σ):      1.834 s ±  0.157 s    [User: 0.482 s, System: 10.333 s]
  Range (min … max):    1.622 s …  2.046 s    5 runs

Benchmark 3: ./target/release/dumac temp/deep
  Time (mean ± σ):     563.1 ms ±  22.6 ms    [User: 57.4 ms, System: 2213.7 ms]
  Range (min … max):   545.1 ms … 595.5 ms    5 runs

Summary
  ./target/release/dumac temp/deep ran
    3.26 ± 0.31 times faster than diskus temp/deep
    5.66 ± 0.42 times faster than du -sh temp/deep

To setup the benchmark:

pip install -r requirements.txt
python setup_benchmark.py

brew install hyperfine
brew install diskus
cargo build --release
hyperfine --warmup 3 --min-runs 3 'du -sh temp/deep' 'diskus temp/deep' './target/release/dumac temp/deep'

Tests

cargo test