wgpu-primitives

Safe, composable GPU prefix scan and unsigned integer radix sort for Rust applications using wgpu.

wgpu-primitives continues the package previously published as wgpu-algorithms beginning with version 0.2.

Features

• Inclusive u32 prefix scan.
• Stable 2-bit LSD radix sort for u32 values.
• Convenience slice APIs that upload, execute, and read back.
• GPU-buffer APIs that record into an existing command encoder.
• Reusable internal scratch storage.
• No unsafe blocks in library code.

Usage

The convenience context is useful for standalone compute programs:

use wgpu_primitives::{Context, Sorter};

#[tokio::main]
async fn main() -> Result<(), wgpu_primitives::Error> {
    let context = Context::init().await?;
    let mut sorter = Sorter::from_context(&context);
    let sorted = sorter.sort(&[10, 4, 7, 1]).await?;

    assert_eq!(sorted, [1, 4, 7, 10]);
    Ok(())
}

Applications that already own a wgpu device should reuse it:

let mut scanner = Scanner::new(&device, &queue);
let mut sorter = Sorter::new(&device, &queue);

scanner.record_scan(&mut encoder, &scan_input, &scan_output, item_count)?;
sorter.record_sort(&mut encoder, &sort_input, &sort_output, item_count)?;
queue.submit(Some(encoder.finish()));

record_scan requires COPY_SRC on the input and COPY_DST | STORAGE on the output. record_sort requires STORAGE on both buffers.

Installation

[dependencies]

wgpu-primitives = "0.2"

Algorithms

The scan recursively computes per-workgroup inclusive prefixes, scans the workgroup totals, and propagates those totals back through the hierarchy.

The radix sort processes two bits per pass. Each of its 16 passes builds four per-workgroup histograms, scans them into global offsets, and stably scatters values between ping-pong buffers.

Performance

Criterion measurements from an RTX 4070 Ti SUPER show why the GPU-buffer API is the primary interface. Resident execution keeps data on the GPU; round trip execution includes upload, allocation, execution, and readback.

At 100M items, resident throughput reached 17.96 billion elements/s for scan and 2.287 billion elements/s for sort. See the full methodology, confidence intervals, backend comparison, and memory accounting.

Development

cargo fmt --all --check

cargo clippy --all-targets --all-features -- -D warnings

cargo test --lib --tests

cargo check --examples --benches

cargo package

cargo bench --bench scan -- --noplot

cargo bench --bench sort -- --noplot

GPU integration tests skip when no compatible adapter is available. CI installs Mesa's Vulkan software adapter so the shader paths execute on Linux.

License

MIT