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WIP: perf(build): the Builder runs the build at normal priority, not below it #779

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dyst wants to merge 1 commit from dyst/Longshot:perf/build-priority into main

dyst commented

2026-11-15 11:51:30 +00:00

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Type: perf · Risk: low · Tested on: Windows 11 (game-free checks) · Needs: Windows on a hybrid Intel CPU (12th gen or later), a first build

Why

On an Intel CPU with efficiency cores, the first build can take over an hour longer than it should. The Builder starts make_game.py below normal priority, and Windows keeps a below-normal process's single-threaded steps (reading the game, the lift) on the efficiency cores while the performance cores sit idle. Project ReLink, a fork of Longshot, found and fixed this (commits 0a74889c and b98adb9e).

What changed

The Builder now runs the build at normal priority. LONGSHOT_LOW_PRIORITY=1 brings back below normal, for a desktop that stays quicker during the build.

builder: Runner.Start in builder/LongshotBuilder/Runner.cs sets ProcessPriorityClass.BelowNormal on make_game.py only when LONGSHOT_LOW_PRIORITY=1.
docs: the switch's row in docs/development.md.
tests: tests/test_builder_own_python.py checks that below normal is only set when the switch asks.

Measurements

Not measured here: this PC isn't a hybrid Intel CPU. ReLink's report was over an hour of a first build on the efficiency cores. The numbers to take are a first build's time with and without LONGSHOT_LOW_PRIORITY=1 on such a CPU.

Flags and settings

One new build switch.

Flag	What it is	Before this PR	After this PR	Effect	Helps / doesn't help / untested	Recommendation
`LONGSHOT_LOW_PRIORITY`	The Builder's build below normal priority	always below normal	unset: normal; `1`: below normal	Normal priority lets Windows run the build's one-process steps on the performance cores	Untested here; helped ReLink's hybrid-CPU players	Unset for everyone; `1` only to keep the desktop quicker during a build

Testing

Tested:

python -I -B tests/test_builder_own_python.py (with the new check), and tests/run_all.py builder docs: 6 passed, 1 skipped (no clang here).
dotnet build builder/LongshotBuilder -c Release: 0 warnings.

Not tested:

A build in the Builder at the new priority.

Must be tested:

Windows, a hybrid Intel CPU (12th gen or later): run a first build with the Builder from this branch, then one with LONGSHOT_LOW_PRIORITY=1. Expect the first to be shorter, with the read and the lift on the performance cores in Task Manager (by hand).

Risks

What could break: the desktop can feel slower during a build, since the compilers now run at normal priority.

Turning it off: LONGSHOT_LOW_PRIORITY=1, or revert the commit.

Compatibility: nothing changes for a player beyond the build's priority.

Checklist

Everyone

One topic.
The title is a Conventional Commit (type(scope): description) of the status line's type.
Why gives the reason plainly and links the issues that fit (the tracker searched).
Measurements has a verdict, or one line saying why there is nothing to measure.
Testing names what was tested, what wasn't, and what must still be tested, where and how.
Rebased on current main.
python -I -B tests/run_all.py passes (any failure that also fails on main is named). (Not yet: only the checks this touches were run; the full run is left to the testing pass.)
No game files, dumps, build output or generated files.
third_party/ untouched (a new folder with a PROVENANCE.md instead).
The license is OK: GPL-3.0-or-later, nothing incompatible and nothing decompiled.

When it applies

AI assistance recorded with Assisted-by: / Co-Authored-By: trailers.
Switches documented (docs/development.md; the README for a menu row) and shipped at their recommended value.
A check under tests/ that reads changed source updated in this PR, not weakened.
Docs updated.

🤖 Generated with Claude Code

**Type:** perf · **Risk:** low · **Tested on:** Windows 11 (game-free checks) · **Needs:** Windows on a hybrid Intel CPU (12th gen or later), a first build ## Why On an Intel CPU with efficiency cores, the first build can take over an hour longer than it should. The Builder starts `make_game.py` below normal priority, and Windows keeps a below-normal process's single-threaded steps (reading the game, the lift) on the efficiency cores while the performance cores sit idle. Project ReLink, a fork of Longshot, found and fixed this (commits [0a74889c](https://github.com/pixl27/ProjectReLink/commit/0a74889c) and [b98adb9e](https://github.com/pixl27/ProjectReLink/commit/b98adb9e)). ## What changed The Builder now runs the build at normal priority. `LONGSHOT_LOW_PRIORITY=1` brings back below normal, for a desktop that stays quicker during the build. - builder: `Runner.Start` in `builder/LongshotBuilder/Runner.cs` sets `ProcessPriorityClass.BelowNormal` on `make_game.py` only when `LONGSHOT_LOW_PRIORITY=1`. - docs: the switch's row in `docs/development.md`. - tests: `tests/test_builder_own_python.py` checks that below normal is only set when the switch asks. ## Measurements Not measured here: this PC isn't a hybrid Intel CPU. ReLink's report was over an hour of a first build on the efficiency cores. The numbers to take are a first build's time with and without `LONGSHOT_LOW_PRIORITY=1` on such a CPU. ### Flags and settings One new build switch. | Flag | What it is | Before this PR | After this PR | Effect | Helps / doesn't help / untested | Recommendation | |---|---|---|---|---|---|---| | `LONGSHOT_LOW_PRIORITY` | The Builder's build below normal priority | always below normal | unset: normal; `1`: below normal | Normal priority lets Windows run the build's one-process steps on the performance cores | Untested here; helped ReLink's hybrid-CPU players | Unset for everyone; `1` only to keep the desktop quicker during a build | ## Testing **Tested:** - `python -I -B tests/test_builder_own_python.py` (with the new check), and `tests/run_all.py builder docs`: 6 passed, 1 skipped (no clang here). - `dotnet build builder/LongshotBuilder -c Release`: 0 warnings. **Not tested:** - A build in the Builder at the new priority. **Must be tested:** - **Windows, a hybrid Intel CPU (12th gen or later):** run a first build with the Builder from this branch, then one with `LONGSHOT_LOW_PRIORITY=1`. Expect the first to be shorter, with the read and the lift on the performance cores in Task Manager (by hand). ## Risks **What could break:** the desktop can feel slower during a build, since the compilers now run at normal priority. **Turning it off:** `LONGSHOT_LOW_PRIORITY=1`, or revert the commit. **Compatibility:** nothing changes for a player beyond the build's priority. ## Checklist ### Everyone - [x] One topic. - [x] The title is a Conventional Commit (`type(scope): description`) of the status line's type. - [x] Why gives the reason plainly and links the issues that fit (the tracker searched). - [x] Measurements has a verdict, or one line saying why there is nothing to measure. - [x] Testing names what was tested, what wasn't, and what must still be tested, where and how. - [x] Rebased on current `main`. - [ ] `python -I -B tests/run_all.py` passes (any failure that also fails on `main` is named). (Not yet: only the checks this touches were run; the full run is left to the testing pass.) - [x] No game files, dumps, build output or generated files. - [x] `third_party/` untouched (a new folder with a `PROVENANCE.md` instead). - [x] The license is OK: GPL-3.0-or-later, nothing incompatible and nothing decompiled. ### When it applies - [x] AI assistance recorded with `Assisted-by:` / `Co-Authored-By:` trailers. - [x] Switches documented (docs/development.md; the README for a menu row) and shipped at their recommended value. - [x] A check under `tests/` that reads changed source updated in this PR, not weakened. - [x] Docs updated. 🤖 Generated with [Claude Code](https://claude.com/claude-code)

dyst added 1 commit

2026-11-15 11:51:30 +00:00

perf(build): the Builder runs the build at normal priority, not below it

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f2c3af12dd

The Builder started make_game.py below normal priority, and the read of the game, the lift and every
compiler inherited it. On a hybrid Intel CPU Windows kept the one-process steps on the efficiency cores,
and the first build lost an hour and more with the performance cores idle (Project ReLink found it,
0a74889c and b98adb9e). Normal priority now; LONGSHOT_LOW_PRIORITY=1 keeps the old one for a desktop that
stays quicker while the game builds.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>