golang/go

runtime: use epoll_pwait2 where available for sub-millisecond timeout precision on Linux

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#53,824 opened on Jul 13, 2022

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NeedsFixPerformancecompiler/runtimehelp wanted

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Description

Linux kernel 5.11 (February, 2021) added the epoll_pwait2 system call. It is exactly like epoll_pwait except that the timeout argument is a struct timespec. This permits specifying a timeout with nanosecond precision, where epoll_pwait and epoll_wait only permit millisecond precision. We should change runtime/netpoll_epoll.go to use epoll_pwait2 when available to get higher precision delays.

CC @golang/runtime

Contributor guide

Research direction
Add epoll pwait2 to runtime/netpoll epoll.go. Detect availability at runtime via kernel version or a probe. Fall back to epoll pwait if unavailable.
Tech stack
go
Domain
backend
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
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.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Linux kernel syscallsGo runtime internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70