smp_processor_id(9)

💅 NAME 💅

okay so bestie, welcome to the smp_processor_id(9) manual page from the Kernel API Manual ✨ — it's literally about getting the current (stable) CPU id, and it's kind of iconic.

🎀 SYNOPSIS 🎀

smp_processor_id

🦋 DESCRIPTION 🦋

This is the normal accessor to the CPU id, and you should use it whenever possible — no cap, it's the default bestie behavior 💖.

The CPU id is stable when:

• IRQs are disabled;
• preemption is disabled;
• the task is CPU affine.

ngl, when CONFIG_DEBUG_PREEMPT=y, we verify these assumptions and hit you with a WARN when smp_processor_id is used while the CPU id is not stable. so if that warning pops up, don't act surprised 💀.

🌈 SEE ALSO 🌈

• Kernel file ./include/linux/smp.h
• on_each_cpu_mask(9)

kisses from the smp_processor_id(9) girlies — source/version: ./include/linux, date: October 2026 🫶💖🎀✨