x86_perf_rdpmc_index(9)

📦 version 7.3.1, in nixpkgs unstable

okay so bestie, this is the x86_perf_rdpmc_index(9) page from the Kernel API Manual 💖 and it's short, but the safety note is important important, so stay with me.

🌸 NAME 🌸

x86_perf_rdpmc_index — return the PMC counter used for event ✨

✨ SYNOPSIS ✨

int x86_perf_rdpmc_index (struct perf_event *event );

🎀 ARGUMENTS 🎀

  • event — the perf_event to which the PMC counter was assigned 🫶

💅 DESCRIPTION 💅

okay so here's the tea ☕: the counter assigned to this performance event may change if interrupts are enabled 😭. so this counter should never be used while interrupts are enabled — periodt, no cap. 🚨

before this function is used to obtain the assigned counter, the event should be checked for validity — using, for example, perf_event_read_local — and that check needs to happen within the same interrupt disabled section in which this counter is planned to be used. iykyk 💅

🫶 RETURN 🫶

The index of the performance monitoring counter assigned to perf_event 💖

🔥 SEE ALSO 🔥

  • Kernel file ./arch/x86/events/core.c — go look, bestie 🌈

xoxo 💖 source/version: ./arch/x86/events · date: October 2026

📦 where this page comes from