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l0ng-ai
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tty7 is split into two Rust processes: a persistent daemon that owns the shells and a GPU-rendered client that talks to it over a local socket. Because the shells live in the daemon, quitting and reopening the app leaves the session intact — detach and reattach, no tmux required. - Persistent sessions — the daemon holds the PTYs and child processes, so closing a window or swapping in a new build never takes a shell down. - Performance — an 11 MB `cat` completes in 95 ms and DOOM-fire renders at 888 fps; the daemon drains the PTY at device speed off the render path. - Shell-aware — new tabs and splits open in the current working directory; zsh, bash, fish, and PowerShell are set up automatically. - Enhanced prompt — inline completion, syntax highlighting, history, and in-terminal search, with rich flag/subcommand signatures for common tools. - Tabs, resizable splits, a command palette, click-to-open links, desktop notifications, eight themes, and CJK/IME input. Native builds for macOS, Windows, and Linux. Built on Zed's gpui and Alacritty's VT core.
143 lines
7.3 KiB
Markdown
143 lines
7.3 KiB
Markdown
# Terminal benchmark harness
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Reproducible throughput/FPS/memory benchmarks for tty7 against Alacritty,
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Ghostty and Kitty, following the methodology of
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[moktavizen/terminal-benchmark](https://github.com/moktavizen/terminal-benchmark).
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macOS only (drivers use `/Applications` paths, BSD `ps`, `pkill`).
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## What it measures
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| Test | Method | Collects |
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| --- | --- | --- |
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| **Plaintext IO** | `cat` an 11 MB text file inside the terminal, 5 runs | elapsed ms per run (lower = better) |
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| **Frame rate** | [DOOM-fire-zig](https://github.com/const-void/DOOM-fire-zig), 5 runs × ~14 s | cumulative average fps per run (higher = better) |
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| **Memory** | cold launch, default shell, idle 6 s | RSS in KB (tty7 = GUI + daemon) |
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The methodology source also measures **input latency**, but with a high-speed
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camera ([is-it-snappy](https://github.com/chadaustin/is-it-snappy)) — that
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can't be automated here and is skipped.
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## Usage
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```bash
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scripts/bench/setup.sh # once: corpus + patched DOOM-fire (+ zig 0.14 if needed)
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cargo build --release # the tty7 under test
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scripts/bench/run_one.sh tty7 io # ALWAYS first: records the reference grid
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scripts/bench/run_one.sh alacritty io # matches tty7's grid automatically
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scripts/bench/run_one.sh ghostty io
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scripts/bench/run_one.sh kitty io
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scripts/bench/run_one.sh tty7 fire # same order for the fire test
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scripts/bench/run_one.sh alacritty fire
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scripts/bench/run_one.sh ghostty fire
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scripts/bench/run_one.sh kitty fire
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scripts/bench/mem.sh # all four terminals, 3 runs each
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```
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Results land in `.bench/results/` (override the work dir with
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`$TTY7_BENCH_DIR`, the tty7 binary with `$TTY7_BIN`).
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**While a run is up: don't type into the window, and don't hide or fully
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occlude it** — macOS throttles occluded windows and the FPS numbers collapse
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(observed: ~950 fps → ~360 fps when the window was hidden mid-run).
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## How it drives each terminal
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Every terminal opens a real window whose *shell* is the benchmark script, so
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the measurement includes the full input path the user experiences:
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- **tty7**: an isolated `--config-dir` under the work dir whose `config.json`
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sets `shell` to the script. GUI + daemon are launched fresh and killed
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(by config-dir-scoped `pkill`) after the run — a daily-driver tty7 and its
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daemon are never touched.
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- **Alacritty**: `--config-file <empty>` (isolates the user's config) plus
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`-o window.dimensions.…` for the grid, `-e` for the script.
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- **Ghostty**: `--config-default-files=false` plus `--window-width/height`
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(cells) and `-e`. `--window-save-state=never` matters: macOS window
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restoration otherwise overrides the requested size.
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- **Kitty**: `--config NONE` plus `-o initial_window_width/height=<n>c` (the
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`c` suffix means cells); the script is passed as trailing args (no `-e`).
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`-o remember_window_size=no` matters: it defaults to yes even under
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`--config NONE`, and the restored size overrides `initial_window_*`.
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Warp is installed here but not benchmarked: closed source, no CLI to run a
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script as the shell, and config isn't file-isolatable. iTerm2/Terminal.app
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would need AppleScript driving and can't cleanly isolate config either.
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Grid fairness: tty7 has no size flag, so its default window is the reference —
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run tty7 first, and the driver reads the recorded `grid:` line to size the
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other terminals identically (cells, not pixels; fonts differ).
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## Why DOOM-fire is patched
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`doom-fire-fps.patch` (applied by `setup.sh`) makes DOOM-fire dump its
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cumulative average fps to `$DOOM_FPS_FILE` every 30 frames. The upstream
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binary only *paints* the number, and recording the output stream to parse it
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back (`script(1)`) is a trap: at 500+ fps the recording grows to gigabytes in
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seconds and its disk writes throttle later runs by 4-8×. The fps definition is
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unchanged — total frames / elapsed seconds since the fire started, the same
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number painted on screen.
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## Recorded baseline (2026-07-03)
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Apple M1 Pro, 32 GB, macOS 26.3.1, grid 155×40, release builds, defaults.
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Optimization = the `VecDeque` replay ring + coalesced `Output` frames +
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backpressure gate (see CHANGELOG "Terminal throughput ~12× faster").
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| Test | tty7 (before) | tty7 (after) | Alacritty | Ghostty | Kitty |
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| --- | ---: | ---: | ---: | ---: | ---: |
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| Plaintext IO, 5-run avg | 2030 ms | **161 ms** | 232 ms | 183 ms | 217 ms |
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| DOOM-fire, 5-run avg | 47 fps | **920 fps** | 542 fps | 533 fps | 546 fps |
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| Memory (GUI+daemon) | 100 MB | **105 MB** | 86 MB | 112 MB | — |
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Kitty (0.47.4) was measured the same day at the same 155×40 grid; its memory
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run was skipped. Upstream's Kitty frame-rate dominance (Linux/Wayland) does
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not reproduce on macOS — here it lands in the same band as Alacritty/Ghostty.
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Diagnosis notes for posterity: macOS PTYs deliver ~1 KiB per read. Before the
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fix, every read into a full 8 MiB `Vec` ring memmoved the whole ring
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(`drain(..overflow)`), eating ~92% of the daemon reader's time — visible as
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"run 1 fast, later runs slow" (the ring fills during run 1). `TTY7_TRACE=1`
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on both the GUI and a foreground daemon prints the per-second accounting that
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localized this.
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## Recorded baseline (2026-07-04, second throughput pass)
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Same machine and grid, all four terminals re-run the same day. Optimization =
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the CHANGELOG "second throughput pass" batch (16 MiB gate, 256 KiB socket
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buffers, client-side Output batching, memchr OSC fast paths, atomic gate,
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QoS promotion).
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All four terminals measured back-to-back in one quiet-machine session:
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| Test | tty7 (before) | tty7 (after) | Alacritty | Ghostty | Kitty |
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| --- | ---: | ---: | ---: | ---: | ---: |
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| Plaintext IO, 5-run avg | 154 ms | **95 ms** | 239 ms | 179 ms | 185 ms |
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| DOOM-fire, 5-run avg | ~760 fps¹ | **888 fps** | 485 fps | 552 fps | 616 fps |
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| Memory (GUI+daemon) | 112 MB | 115 MB | 105 MB | 128 MB | 130 MB |
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¹ The tty7-before numbers were measured while the machine was busy (builds +
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tracing running alongside); on the later quiet machine the same pre-pass
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pipeline would have landed near its 07-03 920 fps. The fire before/after
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delta is therefore mostly ambient load, not the optimization — see the notes
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below. After the pass, quiet-machine fire runs tightened to 882–894 (±0.7%).
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Notes for interpreting these numbers, learned the hard way:
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- **The day's fps band matters more than the run.** The same pre-pass binary
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that recorded 920 fps on 07-03 measured 728–857 on 07-04; competitors
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reproduced within ±3%. tty7's fire number is drain-rate-bound and therefore
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sensitive to ambient machine load in a way the (slower) competitors aren't.
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Only compare tty7-vs-tty7 fire numbers from the same session.
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- **DOOM-fire is producer-bound, not terminal-bound, at this level.** Under a
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raw do-nothing PTY reader it produces ~96 MB/s at a constant ~87 KB/frame —
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i.e. ~1050–1100 fps is the machine's ceiling for *any* terminal, and fps
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scales linearly with drain rate (capped-drain probe: 95 MB/s → 1092 fps,
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60 MB/s → 690 fps). tty7's steady seconds already drain at 93–98 MB/s; the
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gap to the ceiling is whole seconds where the *producer* gets descheduled.
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- **`cat` completion time is a drain benchmark, not a render benchmark.** The
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16 MiB gate lets an 11 MB burst leave the PTY at device speed while the
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client parses behind; sustained plaintext drain is 148 MB/s against a
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~170 MB/s raw-reader ceiling (the client's VT parser, ~0.7 core, is the
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remaining sustained-throughput limit).
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