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Code at the speed of thought – Zed is a high-performance, multiplayer code editor from the creators of Atom and Tree-sitter.
6afac23e4a
## Motivation
Miniprofs of Zed dropping frames showed foreground thread stalls of
711.56 ms, 641.01 ms, and 221.99 ms from the `edit_file_tool`. The new
benchmark isolated `StreamingDiff::push_new` as one of the expensive
phases so this PR aims to speed it up so we can avoid dropping more
frames in the future.
## Benchmark methodology
I had an agent create a Criterion suite with four deterministic Rust
edit fixtures: tiny localized rewrite, small localized rewrite, many
small changes, and helper block insertions.
Benchmarked with:
```sh
cargo bench -p streaming_diff --bench streaming_diff --profile release-fast -- --warm-up-time 1 --measurement-time 2
```
The benchmark binary was also recorded under `xctrace` CPU Counters to
inspect CPU samples before and after the change.
## Results
`StreamingDiff::push_new` improved across all fixtures:
| Benchmark | Before | After | Improvement |
|---|---:|---:|---:|
| `tiny_function_rewrite` | ~10.81 ms | ~6.91 ms | ~36% faster |
| `small_function_rewrite` | ~51.02 ms | ~35.39 ms | ~31% faster |
| `medium_many_small_changes` | ~130.71 ms | ~83.83 ms | ~36% faster |
| `medium_insertions` | ~120.52 ms | ~79.90 ms | ~34% faster |
The `xctrace` baseline showed samples in `Hash::hash`,
`RandomState::hash_one`, `HashMap::insert`, and
`RawTable::reserve_rehash`. After replacing the map with two `Vec<u32>`
row buffers, the hash table frames disappeared from the top samples.
The speedup comes from removing hash work from the DP inner loop and
replacing scattered hash table probes with contiguous row buffer access
(better cache hits 🏎️). The trace did not include direct cache miss
counts, but this layout is likely more cache friendly because it
replaces hash table access with a continuous line of memory (the
`Vec`s).
Release Notes:
- N/A
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| .cargo | ||
| .cloudflare | ||
| .config | ||
| .factory | ||
| .github | ||
| .zed | ||
| assets | ||
| ci | ||
| crates | ||
| docs | ||
| extensions | ||
| legal | ||
| nix | ||
| script | ||
| tooling | ||
| .git-blame-ignore-revs | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .prettierrc | ||
| .rules | ||
| AGENTS.md | ||
| Cargo.lock | ||
| Cargo.toml | ||
| CLAUDE.md | ||
| clippy.toml | ||
| CODE_OF_CONDUCT.md | ||
| compose.yml | ||
| CONTRIBUTING.md | ||
| debug.plist | ||
| default.nix | ||
| Dockerfile-collab | ||
| Dockerfile-collab.dockerignore | ||
| Dockerfile-cross.dockerignore | ||
| Dockerfile-distros | ||
| Dockerfile-distros.dockerignore | ||
| flake.lock | ||
| flake.nix | ||
| GEMINI.md | ||
| LICENSE-AGPL | ||
| LICENSE-APACHE | ||
| LICENSE-GPL | ||
| livekit.yaml | ||
| lychee.toml | ||
| Procfile | ||
| Procfile.all | ||
| Procfile.web | ||
| README.md | ||
| renovate.json | ||
| REVIEWERS.conl | ||
| rust-toolchain.toml | ||
| rustfmt.toml | ||
| shell.nix | ||
| typos.toml | ||
Zed
Welcome to Zed, a high-performance, multiplayer code editor from the creators of Atom and Tree-sitter.
Installation
On macOS, Linux, and Windows you can download Zed directly or install Zed via your local package manager (macOS/Linux/Windows).
Other platforms are not yet available:
- Web (tracking discussion)
Developing Zed
Contributing
See CONTRIBUTING.md for ways you can contribute to Zed.
Also... we're hiring! Check out our jobs page for open roles.
Licensing
License information for third party dependencies must be correctly provided for CI to pass.
We use cargo-about to automatically comply with open source licenses. If CI is failing, check the following:
- Is it showing a
no license specifiederror for a crate you've created? If so, addpublish = falseunder[package]in your crate's Cargo.toml. - Is the error
failed to satisfy license requirementsfor a dependency? If so, first determine what license the project has and whether this system is sufficient to comply with this license's requirements. If you're unsure, ask a lawyer. Once you've verified that this system is acceptable add the license's SPDX identifier to theacceptedarray inscript/licenses/zed-licenses.toml. - Is
cargo-aboutunable to find the license for a dependency? If so, add a clarification field at the end ofscript/licenses/zed-licenses.toml, as specified in the cargo-about book.
Sponsorship
Zed is developed by Zed Industries, Inc., a for-profit company.
If you’d like to financially support the project, you can do so via GitHub Sponsors. Sponsorships go directly to Zed Industries and are used as general company revenue. There are no perks or entitlements associated with sponsorship.