LIBPFM(3)

🌸 NAME 🌸

okay so bestie, welcome to the LIBPFM(3) page from the Linux Programmer's Manual 💖. This one is all about libpfm_intel_spr_unc_cha — support for the Intel IcelakeX Server CHA uncore PMU. yes, that is the whole name, and no we are not abbreviating it, periodt. 💅

✨ SYNOPSIS ✨

here's the incantation, copy it exactly:

#include <perfmon/pfmlib.h>

PMU name: spr_unc_cha[0-59]
PMU desc: Intel SapphireRapids CHA uncore PMU

🦋 DESCRIPTION 🦋

The library is out here supporting the Intel SapphireRapids CHA (coherency and home agent) uncore PMU. One CHA-box PMU per physical core — that's the setup. So there are up forty identical CHA PMU instances numbered from 0 up to possibly 59. On dual-socket systems, that number refers to the CHA PMUs on the socket where the program runs. 🫶

Each CHA PMU implements 4 generic counters. lowkey iconic. ✨

💅 MODIFIERS 💅

These are the modifiers supported on the Intel SapphireRapids CHA uncore PMU:

• e — turns on edge detection, meaning count only when there's a state transition from no occurrence of the event to at least one occurrence. You must pair this with a threshold modifier (t) whose value is greater or equal to one. It's a boolean modifier. 🦋
• t — sets the threshold value. If it's non-zero, the counter counts the number of CHA clockticks where the number of occurrences of the event is greater or equal to the threshold. It's an integer modifier, values in the range [0:255]. ✨
• i — flips the threshold (t) test from strictly greater than to less or equal to. It's a boolean modifier. 💅

👑 AUTHORS 👑

Stephane Eranian <eranian@gmail.com> — the mastermind, the icon, the blueprint. bow down. 👑

catch u later, bestie — this was the January, 2024 edition of LIBPFM(3), part of the Linux Programmer's Manual. mwah 💋