andros
fb45f6a582
Mermaid's xychart-beta cannot draw grouped bars or a legend: two bar series overlap on the same axis position, so the paired GPU-vs-cairo comparison was unreadable. Render the charts as images with real grouped bars, value labels and a legend (bench/make-charts.py), and embed them from .github/assets/.
45 lines
1.8 KiB
Markdown
45 lines
1.8 KiB
Markdown
# Benchmark harness
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Redisplay-throughput benchmarks: the GPU backend vs stock Emacs, on the **same binary** (GPU on vs off). These produce the tables in the top-level `README.md`.
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## Requirements
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- An Emacs built `--with-gpu` (point `EMACS` at it).
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- `python3` with Pillow and numpy.
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- `xvfb-run` (only for `run-bench-hires.sh`).
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## Run (GNU/Linux, X11)
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```sh
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# On-screen, ~1616x912 frame on the current display:
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EMACS=/path/to/gpu/emacs ./run-bench.sh [RUNS]
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# Headless 4K render throughput (GPU renders to an FBO, no present):
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EMACS=/path/to/gpu/emacs ./run-bench-hires.sh [RUNS]
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```
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Each prints a stock-vs-GPU fps table with the speedup ratio. `RUNS` defaults to 3; the median is reported.
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## What it measures
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Five workloads, each forcing `(redisplay t)` per frame (median of N runs, 80-frame warm-up first). GPU side runs vsync off (`GL_NO_VSYNC=1`) to measure frame cost, not the 60 Hz cap.
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| Workload | Stresses |
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|---|---|
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| `line-scroll` | one line/frame: few new glyphs (cairo is strong here) |
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| `page-scroll` | one window/frame: many new glyphs |
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| `full-redraw` | `redraw-frame`: everything repainted |
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| `typing` | one `self-insert`/frame: minimal dirty rect, floor is one buffer swap |
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| `image-scroll` | scrolling images: cached texture re-composite vs cairo re-blit from CPU |
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Buffer: 8000-line font-locked Emacs Lisp; image test uses a synthesized PNG.
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Absolute numbers depend on GPU, driver and display server. The meaningful quantity is the **ratio** between the two modes on the same machine.
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## Files
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- `gl-bench.el` — the workloads. Reads `GL_MODE` (`gpu`/`vanilla`), `GL_BENCH_COLS`/`GL_BENCH_ROWS`, `GL_BENCH_OUT`. The scripts set these.
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- `run-bench.sh` — on-screen comparison.
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- `run-bench-hires.sh` — headless 4K render-throughput comparison.
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- `make-charts.py` — regenerates the README chart images from the numbers (matplotlib).
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