cpuwalk.bt(8)

📦 version 0.17.0, in debian bookworm

💅 cpuwalk.bt — the tea ☕

okay bestie, gather round, because we're talking about cpuwalk.bt from the System Manager's Manual (section 8, we love a system manager moment) ✨

🌸 NAME 🌸

cpuwalk.bt — literally samples which CPUs are executing processes. yeah. that's the whole vibe. and it uses bpftrace/eBPF to do it 🦋

🎀 SYNOPSIS 🎀

cpuwalk.bt

that's it. that's the whole thing. no args, no flags, just vibes 👑

✨ DESCRIPTION ✨

so here's what's happening: this tool samples your CPUs at 99 Hertz, and then prints a histogram showing which CPUs were actually active 🔥

and why 99 Hertz specifically, you ask? because 99 Hertz is used to avoid lockstep sampling — which would skew your results. like, we do NOT do skewed results in this house 🙅‍♀️ no cap.

this tool can help you figure out if your application's workload is evenly using the CPUs, or if there's an imbalance problem going on. it's giving detective energy 🔍

⚠️ okay important: since this uses BPF, only the root user can use this tool. root only. periodt. 💅

🧚 REQUIREMENTS 🧚

  • CONFIG_BPF
  • bpftrace

both. you need both. that's the entry fee bestie 🎟️

🌈 EXAMPLES 🌈

sample CPUs and print a summary on Ctrl-C:

# cpuwalk.bt

so you run it, you watch it do its lil thing, and then you hit Ctrl-C and it gives you the summary. iconic behavior honestly 😭

🍓 FIELDS 🍓

  • 1st, 2nd — the CPU is shown in the first field, right after the "[". as for the second field? disregard it. we don't know her. ignore her. 🙈
  • 3rd — a column showing the number of samples for this CPU 📊
  • 4th — this is an ASCII histogram representing the count column ✨

🫶 OVERHEAD 🫶

this should be negligible. tiny. basically free. we love a low-cost queen 👑

💜 SOURCE 💜

this is from bpftrace 💖

https://github.com/iovisor/bpftrace

also, look in the bpftrace distribution for a companion _examples.txt file containing example usage, output, and commentary for this tool. it's like the director's commentary track but for your tool 🎬

🦋 OS 🦋

Linux 🐧

💀 STABILITY 💀

Unstable — in development. she's still growing. still evolving. still in her development era 🌱

👑 AUTHOR 👑

Brendan Gregg 💖

⭐ SEE ALSO ⭐

okay and one last thing before you go, bestie — this little love letter came from USER COMMANDS, dated 2018-09-08, and it lives at cpuwalk.bt(8). write that down. or don't. it's on the page either way 💅✨🌈

📦 where this page comes from