LIBPFM(3)

💖 LIBPFM_INTEL_SKX_UNC_M2M 💖

okay bestie, so this is a page from the Linux Programmer's Manual, section 3 (that's the library-functions section, iykyk), and it's literally all about the Intel Skylake X Server M2M uncore PMU. yes, that's a mouthful. we're doing this together. 🫶

✨ NAME ✨

libpfm_intel_skx_unc_m2m — support for the Intel Skylake X Server M2M uncore PMU, no cap 💅

🌸 SYNOPSIS 🌸

#include <perfmon/pfmlib.h>

PMU name: skx_unc_m2m[0-1]

PMU desc: Intel Skylake X Server Mesh-2-Memory uncore PMU

like. the vibes are immaculate and the include is right there. put it in your file and you're set. 🦋

👑 DESCRIPTION 👑

The library supports the Intel Skylake X server system configuration unit M2M uncore PMU.

that's the whole thing, bestie. the library has your back for this particular PMU. it's giving "specialist support, but make it iconic." ⭐

🎀 MODIFIERS 🎀

The following modifiers are supported on the Intel Skylake X server M2M uncore PMU:

• e — Enable edge detection, i.e., count only when there is a state transition from no occurrence of the event to at least one occurrence. This modifier must be combined with a threshold modifier (t) with a value greater or equal to one. This is a boolean modifier.

not me warning you: e does NOT work alone. you have to pair it with t and that threshold value has to be greater or equal to one. no t, no counting. periodt. 🙈

• t — Set the threshold value. When set to a non-zero value, the counter counts the number of HA cycles in which the number of occurrences of the event is greater or equal to the threshold. This is an integer modifier with values in the range [0:15].

the range is [0:15] fr fr, don't go wandering outside it. and yes, non-zero is what actually makes it count.

• i — Invert the meaning of the threshold or edge filter. If set, the event counts when strictly less than N occurrences occur per cycle if threshold is set to N. When invert is set, then threshold must be set to non-zero value. If set, the event counts when the event transitions from occurring to not occurring (falling edge) when edge detection is set. This is a boolean modifier.

so i is the "flip it" girlie. two whole moods: - with threshold set to N, it counts when strictly less than N occurrences happen per cycle. and listen — if you set i, threshold must be non-zero. non-negotiable. 💀 - with edge detection on, it counts the falling edge instead: when the event transitions from occurring to not occurring. lowkey iconic behavior.

🌈 AUTHORS 🌈

Stephane Eranian <eranian@gmail.com>

shoutout to the author, absolute main character energy. 👑

and that's the whole page bestie, you ate. this was LIBPFM(3) from the Linux Programmer's Manual, dated January, 2018 — go forth and count those M2M uncore events. slay, stay hydrated, and remember to set your threshold. 🧚💜