CPUPLUGD(8)

🌸 CPUPLUGD(8) — like, the CPU & memory hotplug daemon for Linux on System z 🌸

okay bestie, so this one's from the System Manager's Manual and honestly it's kind of iconic — it's cpuplugd, the Linux on System z CPU and memory hotplug daemon. she's out here running your whole vibe check on CPUs, no cap 💅

✨ SYNOPSIS ✨

cpuplugd [OPTIONS]

🦋 DESCRIPTION 🦋

so the cpuplugd daemon literally dynamically enables and disables CPUs, and also increases or decreases the cooperative memory management (CMM) page pool — all based on a set of rules. it's giving main character energy for your system resources fr fr 👑

and the way that it's polite?? when the daemon is stopped, the size of the CMM page pool and the number of active CPUs are reset to the values they had before cpuplugd was started. she cleans up after herself, we love to see it 🫶

this program can be used to control the number of CPUs for Linux on z/VM and for Linux in LPAR mode. but heads up — the memory hotplug feature (CMM page pool) applies to Linux on z/VM only. iykyk, not every setup gets the memory magic 💖

also, the cpuplugd daemon stops any CPU hot-plug operations when the system switches to vertical polarization, thus avoiding possible performance penalties. lowkey a protective queen 🌈

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🎀 OPTIONS 🎀

• -c or --config <configuration file> — specify the absolute path to the configuration file. this option is mandatory (no skipping, bestie 😭). the default configuration file can be found in /etc/cpuplugd.conf.
• -f or --foreground — run in the foreground and not as daemon. if this option is omitted, the program runs in the background. so like, foreground is the "watch me do it" mode ✨
• -h or --help — print usage message and exit. your lil cheat sheet 🎀
• -v or --version — print Version information and exit. (yes, lowercase -v is version — do not mix her up with her sister 👀)
• -V or --verbose — print verbose messages to stdout (when running in foreground) or to syslog otherwise. this option is mainly used for debugging purposes. capital -V = chatty mode, very "tell me everything" energy 💀

ok quick vibe check: -v is version, -V is verbose. case matters, bestie, don't do it to yourself 🙈

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🌸 EXAMPLES 🌸

to test a setup, start cpuplugd in foreground mode using verbose output:

cpuplugd -V -f -c /etc/cpuplugd.conf

for daemon mode, start cpuplugd from an init script as follows:

cpuplugd -c /etc/cpuplugd.conf

🧚 SEE ALSO 🧚

cpuplugd.conf(5) — go read her config bestie, that's where the rules live 💜

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and that's the whole page, bestie — slay ✨ this lil beauty comes from s390-tools, dated May 2011, and she's filed under CPUPLUGD(8). periodt. 💅🎀