PMDAZSWAP(1)

💖 PMDAZSWAP 💖

okay so bestie, we're in the pmdazswap(1) page — that's the General Commands Manual, one of the Performance Co-Pilot crew — and it's literally all about the zswap PMDA. let's get into it 🦋

✨ NAME ✨

pmdazswap — the zswap (compressed swap) PMDA. that's it, that's the name, no notes 💅

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🌸 DESCRIPTION 🌸

so pmdazswap is a Performance Metrics Domain Agent (PMDA) — and what it does is export metric values about compressed swap operation, as tracked by the zswap Linux kernel module. it's giving observability, it's giving kernel-module-witness energy 👑

now, what even is zswap? okay so zswap is a lightweight compressed cache for swap pages. what it does is take pages that are in the process of being swapped out and it attempts to compress them into a dynamically allocated RAM-based memory pool. yes, really. it trades CPU cycles for potentially reduced swap I/O 🌈 and lowkey that tradeoff can also result in a performance improvement if reads from the compressed cache are faster than reads from a swap device. main character tradeoff fr fr.

this PMDA exports metrics about:

• pool size 🫧
• number of pages stored 🍓
• and various counters for the reasons pages are rejected 💀

🎀 INSTALLATION 🎀

install the zswap PMDA by using the Install script as root:

# cd $PCP_PMDAS_DIR/zswap
# ./Install

to uninstall, do the following as root:

# cd $PCP_PMDAS_DIR/zswap
# ./Remove

heads up bestie: pmdazswap is launched by pmcd(1) and should never be executed directly. do not do it. i'm so serious 🙈

the Install and Remove scripts notify pmcd(1) when the agent is installed or removed — so they handle the whole vibe check for you ✨

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💜 FILES 💜

• $PCP_PMDAS_DIR/zswap/Install — installation script for the pmdazswap agent 🛠️
• $PCP_PMDAS_DIR/zswap/Remove — undo installation script for the pmdazswap agent 🧹
• $PCP_LOG_DIR/pmcd/zswap.log — default log file for error messages from pmdazswap 📓

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🦋 PCP ENVIRONMENT 🦋

environment variables with the prefix PCP_ are used to parameterize the file and directory names used by PCP. on each installation, the file /etc/pcp.conf contains the local values for these variables. and the $PCP_CONF variable may be used to specify an alternative configuration file, as described in pcp.conf(5) — iykyk 🌟

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⭐ SEE ALSO ⭐

PCPIntro(1) and pmcd(1). that's the reading list, bestie, go read them 🫶

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okay and that's the whole page! this one came from the Performance Co-Pilot peeps (that's the source — PCP, and the manual section is PMDAZSWAP(1) in General Commands Manual) 💖 slay, you now know everything about compressed swap metrics. periodt ✨💅