oomkill.bt(8)

👑 oomkill.bt — bestie edition

okay so real quick: this is the manual page for oomkill.bt from the System Manager's Manual section 8 (that's the system-admin-y section, iykyk). Let's get into it 💅

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✨ NAME ✨

oomkill.bt — Trace OOM killer. Uses bpftrace/eBPF.

🎀 SYNOPSIS 🎀

oomkill.bt

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

🦋 DESCRIPTION 🦋

So what this little icon does is trace the kernel out-of-memory killer, and it prints out the basic details — including the system load averages at the exact moment of the OOM kill. Why do we care? Because it gives you context on what the system was doing at that time: was it getting busier, or was it just steady? The load averages tell you. 🌸

This tool is also lowkey perfect for customizing for your own investigations. Like, for example, you could add other task_struct details at the time of the OOM, or add other commands to run at the shell. Make it yours bestie 💖

Since this uses BPF, only the root user can use this tool. Not negotiable, sorry 😭

🌈 REQUIREMENTS 🌈

• CONFIG_BPF
• bpftrace

💜 EXAMPLES 💜

Trace OOM kill events:

# oomkill.bt

🍓 FIELDS 🍓

• Triggered by ... — The process ID and process name of the task that was running when another task was OOM killed.
• OOM kill of ... — The process ID and name of the target process that was OOM killed.
• loadavg — Contents of /proc/loadavg. The first three numbers are 1, 5, and 15 minute load averages (where the average is an exponentially damped moving sum, and those numbers are constants in the equation); then there is the number of running tasks, a slash, and the total number of tasks; and then the last number is the last PID to be created.

🧚 OVERHEAD 🧚

Negligible. Like, basically nothing. She's lightweight, she's polite, she's not gonna tank your box 🫶

🔥 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.

This is a bpftrace version of the bcc tool of the same name. The bcc tool may provide more options and customizations.

https://github.com/iovisor/bcc

⭐ OS ⭐

Linux

💀 STABILITY 💀

Unstable — in development. (she's growing, she's evolving, be gentle 🙈)

👑 AUTHOR 👑

Brendan Gregg

🌟 SEE ALSO 🌟

dmesg(1)

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and that's the whole page, bestie 💖 this one's a USER COMMANDS situation, dated 2018-09-07, and it's oomkill.bt(8) — go forth and catch those OOM kills, you got this, periodt 💅✨