LIBPFM(3)

📦 version 4.14.1, in arch rolling, centos-stream 10, centos-stream 9, debian trixie, fedora 43, fedora 44, nixos 26.05, nixpkgs unstable, ubuntu questing, ubuntu resolute, ubuntu stonking

💖 LIBPFM(3) 💖 — straight out of the Linux Programmer's Manual, section 3

okay bestie, sit down, hydrate, because we're talking about a very specific little corner of perfmon and honestly? it's iconic.

✨ NAME ✨

libpfm_intel_gnr_unc_imc — the support in libpfm for the Intel GraniteRapids Server Integrated Memory Controller (IMC) uncore PMU. yes that's a mouthful. yes it slays anyway. 💅

🌸 SYNOPSIS 🌸

#include <perfmon/pfmlib.h>
  • PMU name: gnr_unc_imc[0-11]
  • PMU desc: Intel GraniteRapids Server IMC uncore PMU

like, there are twelve of them, 0 through 11, and they're all just vibing there waiting for you. 🫶

🦋 DESCRIPTION 🦋

so the library supports the Intel GraniteRapids Server Integrated Memory Controller (IMC) uncore PMU. that's the whole thing. it's giving "short and confident." ✨

🎀 MODIFIERS 🎀

these are the modifiers supported on the Intel GraniteRapids server IMC uncore PMU, and ngl you're gonna want to know them:

  • e — turns on edge detection, meaning you only count when there's a state transition from no occurrence of the event to at least one occurrence. cute, right? BUT: this modifier must be combined with a threshold modifier (t) that has a value greater than or equal to one. it's a boolean modifier, so no numbers, just vibes. 🔥
  • t — sets the threshold value. when you set it to something non-zero, the counter counts the number of IMC cycles in which 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]. 🍓 and oh — sneaking in right behind it is i: Invert the threshold (t) test, flipping it from strictly greater than to less or equal to. that one's a boolean modifier too. the way this one was just tucked into the t paragraph?? not me side-eyeing the formatting 😭 but it's real and it matters, so keep it in your notes. 📝

👑 AUTHORS 👑

Stephane Eranian <eranian@gmail.com> — king behavior, honestly. 💜

k that's the whole page, bestie. it's from February, 2025, it's LIBPFM(3), and you now know more about GraniteRapids IMC uncore than like 90% of the group chat. go forth and perf. 🌈⭐

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