golang/go

x/sys/unix: add darwin efficiency core scheduling integer constants

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#75529 opened on Sep 18, 2025

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NeedsFixcompiler/runtimehelp wanted

Description

Proposal Details

Darwin has the ability to force scheduling to the efficiency cores on Apple Silicon through the setpriority syscall, but the integer constants currently aren't exposed.

I think changing the regex here: cs.opensource.google / github from PRIO_(PROCESS|PGRP|USER) to PRIO_(PROCESS|PGRP|USER|DARWIN_THREAD|DARWIN_PROCESS|DARWIN_BG|DARWIN_NONUI) or PRIO_(PROCESS|PGRP|USER|DARWIN_(THREAD|PROCESS|BG|NONUI)) would result in being able to force execution onto an efficiency core.

As an additional reference, here's the CPython PR: https://github.com/python/cpython/issues/103545

I'd love to actually land this change in Go myself, but frankly don't know where to begin.

Contributor guide

Tech stack
go
Domain
api
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Go basicsUnix syscallsRegex knowledgeGo contribution workflow
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
Focus on the mkerrors.sh file in the golang/sys repository. Modify the regex on line 583 (currently 'PRIO (PROCESS|PGRP|USER)') to include 'PRIO DARWIN THREAD', 'PRIO DARWIN PROCESS', 'PRIO DARWIN BG', and 'PRIO DARWIN NONUI'. After editing, run the script to regenerate the constants. Then create a pull request with the changes. Refer to the linked CPython issue for additional context on the Darwin efficiency core scheduling constants.