trueno-zram

Table of Contents

• Installation
• Usage
• Architecture
• API Reference
• Examples
• Testing
• Contributing
• License

19x faster than kernel zram on AVX-512 systems

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Features

• 19x faster decompression than kernel zram via AVX-512 ZSTD
• Adaptive compression with entropy-based algorithm selection (LZ4/ZSTD)
• Userspace block device via Linux ublk for zero-copy I/O
• SIMD-accelerated compression on x86_64 (AVX2/AVX-512) and AArch64 (NEON)

Why trueno-zram?

Kernel zram uses scalar LZ4 limited to 1.3 GB/s. trueno-zram uses AVX-512 ZSTD achieving 25 GB/s decompression. Same workload, 19x faster.

┌─────────────────────────────────────────────────────────────┐
│  Decompression Throughput (same-fill pages)                 │
├─────────────────────────────────────────────────────────────┤
│  trueno-zram ZSTD  ████████████████████████████  25.3 GB/s  │
│  Kernel zram LZ4   █░                             1.3 GB/s  │
└─────────────────────────────────────────────────────────────┘

Installation

# Install
cargo install trueno-ublk

# Create 8GB compressed swap (requires root)
sudo trueno-ublk create --size 8G --algorithm zstd1 --high-perf

# Enable as swap
sudo mkswap /dev/ublkb0 && sudo swapon -p 150 /dev/ublkb0

# Verify
swapon --show

Problems It Solves

For Power Users (Workstations, Servers)

Problem	Without trueno-zram	With trueno-zram
ML Training Memory Spikes	OOM killer terminates training	8GB+ compressed swap absorbs spikes at 25 GB/s
Parallel Compilation	cargo build with 48 threads → OOM	Overflow handled, builds complete
Unused AVX-512	Kernel ignores your CPU's SIMD	Full AVX-512 utilization → 19x speedup
GPU Memory Pressure	Slow disk swap stalls CUDA	Fast RAM swap keeps GPU fed
Multi-Project Development	System freezes, requires reboot	Smooth operation under memory pressure

For Everyone

Problem	Without	With trueno-zram
Cloud VMs (4-8GB RAM)	Pay 2x for larger instance	Effective 2x RAM via compression
Laptop SSD Lifespan	10-100GB swap writes/day	90% stays in RAM, SSD lasts 5x longer
Raspberry Pi / Edge	SD card swap at 10 MB/s	Compressed RAM at GB/s speeds
Database Latency	Query timeouts when swapping	<1ms swap latency, queries complete
CI/CD Build Servers	OOM kills parallel builds	Builds succeed without RAM upgrades

Performance

Benchmarked on AMD Threadripper 7960X with AVX-512:

Metric	trueno-zram	Kernel zram	Speedup
ZSTD Decompress	25.3 GB/s	1.3 GB/s	19x
ZSTD Compress	15.5 GB/s	1.3 GB/s	12x
Same-fill Read	7.9 GB/s	171 GB/s*	-
Random 4K IOPS	666K	~1.5M	0.4x

*Kernel same-fill uses direct memset, not compression.

Examples

# Algorithm comparison benchmark
cargo run --release --example zstd_vs_lz4

# Tiered storage architecture demo
cargo run --release --example tiered_storage

# Visualization integration demo
cargo run --release --example visualization_demo

Example Output: ZSTD vs LZ4

W0-ZEROS (same-fill pages)
Algorithm            Compress     Decompress    Ratio
--------------------------------------------------------
  LZ4              5.78 GiB/s      0.78 GiB/s   157.5x
  ZSTD-1           3.29 GiB/s     25.28 GiB/s   372.4x

  ZSTD-1 speedup: 32x faster decompression

Usage

use trueno_zram_core::{CompressorBuilder, Algorithm, PageCompressor, PAGE_SIZE};

// Create compressor with ZSTD level 1 (fastest)
let compressor = CompressorBuilder::new()
    .algorithm(Algorithm::Zstd1)
    .build()?;

// Compress a 4KB page
let page = [0u8; PAGE_SIZE];
let compressed = compressor.compress(&page)?;
let decompressed = compressor.decompress(&compressed)?;

assert_eq!(page, decompressed);

API Reference

trueno-ublk create    # Create compressed RAM device
trueno-ublk list      # List devices
trueno-ublk stat      # Show statistics
trueno-ublk top       # Interactive TUI dashboard
trueno-ublk benchmark # Run benchmarks with JSON/HTML output
trueno-ublk entropy   # Analyze file entropy

High-Performance Modes

# High-perf: polling mode, larger batches
sudo trueno-ublk create --size 8G --algorithm zstd1 --high-perf

# Max-perf: highest throughput (high CPU usage)
sudo trueno-ublk create --size 8G --algorithm zstd1 --max-perf --queues 4

# Tiered: entropy-based routing to kernel zram
sudo trueno-ublk create --size 8G --backend tiered --entropy-routing

Architecture

┌─────────────────────────────────────────────┐
│            trueno-ublk CLI                   │
│  (create, list, stat, top, benchmark)        │
├─────────────────────────────────────────────┤
│         Userspace Block Device               │
│  (io_uring, ublk protocol, queue mgmt)       │
├──────────┬──────────────────────────────────┤
│ Adaptive │  trueno-zram-core                 │
│ (entropy │  (SIMD compression engine)        │
│  routing)│                                   │
├──────────┴──────────┬───────────────────────┤
│  ZSTD (AVX-512)     │  LZ4 (SIMD)           │
│  25 GB/s decompress │  5.8 GB/s compress     │
└─────────────────────┴───────────────────────┘

• Core: SIMD-accelerated page compression/decompression (4KB pages)
• Adaptive: Entropy-based algorithm selection routes pages to optimal compressor
• Ublk: Linux userspace block device using io_uring for zero-copy I/O
• Tiered: Entropy routing to kernel zram for incompressible data

Testing

cargo test -p trueno-zram-core    # Core compression tests
cargo test                        # All workspace tests
cargo bench -p trueno-zram-core   # Compression benchmarks
make quality-gate                 # Full quality gate: lint + test + coverage

Property-based tests verify compression roundtrip invariants across page patterns (zeros, random, mixed).

Project Structure

Crate	Description
trueno-zram-core	SIMD compression library (LZ4, ZSTD, AVX-512)
trueno-zram-adaptive	Entropy-based algorithm selection
trueno-ublk	Userspace block device daemon

Requirements

• Linux Kernel >= 6.0 (ublk support)
• x86_64 with AVX2/AVX-512 or AArch64 with NEON
• Rust >= 1.82.0

Benchmarking

# Compression library benchmark
cargo bench -p trueno-zram-core

# Device I/O benchmark (requires root)
sudo fio --name=test --filename=/dev/ublkb0 --rw=randread \
    --bs=4k --numjobs=4 --iodepth=32 --runtime=10

# Generate HTML benchmark report
trueno-ublk benchmark --size 4G --format html -o report.html

Documentation

• Book - Comprehensive guide
• API Docs - Library documentation
• Visualization Guide - TUI and metrics

Contributing

Contributions are welcome! Please see the CONTRIBUTING.md guide for details.

Areas of interest:

• Performance optimizations (SIMD, compression algorithms)
• New compression algorithm support
• Documentation improvements
• Bug fixes

MSRV

Minimum Supported Rust Version: 1.82

License

MIT OR Apache-2.0

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Part of the PAIML ecosystem: trueno | aprender | bashrs

25 GB/s decompression. 19x faster than kernel zram. Use it today.