VCPUSTAT(8)

💅 VCPUSTAT(8) — Linux on Power Service Tools

okay bestie, meet vcpustat(8) — the Linux on Power service tool that reports logical partition (LPAR) dispatch statistics, no cap. It’s giving “niche but iconic,” and we’re gonna read it together. 🫶

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🌸 NAME

vcpustat — Report logical partition (LPAR) dispatch statistics.

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✨ SYNOPSIS

/usr/sbin/vcpustat [ options ] [ <interval> [ count ] ]

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💫 DESCRIPTION

The vcpustat command provides a report of logical processor (vcpu) dispatch statistics. It displays logical processor dispatch dispersions, relative to the previous dispatch, as well as relative to the logical processor’s home node as indicated by the Hypervisor. Periodt. 💅

When you run vcpustat with no options, it generates a single report containing raw dispatch counts since the last time statistics were enabled. That’s useful if dispatch statistics have already been enabled persistently using the -e option, iykyk. ✨

The following information is displayed in the report for each logical processor:

🌀 dispatch dispersions

This represents logical processor dispatch dispersions, relative to the previous dispatch, and includes these columns:

• total — Indicates the total number of dispatches of this logical processor. This is only displayed if numeric or raw values are being shown.
• core — Indicates the number of times this logical processor was dispatched within the same core.
• chip — Indicates the number of times this logical processor was dispatched in a different core, but within the same chip.
• socket — Indicates the number of times this logical processor was dispatched in a different chip, but within the same socket. This is only seen on Multi Chip Modules.
• cec — Indicates the number of times this logical processor was dispatched outside the socket.

🌀 numa dispersions

This represents logical processor dispatch dispersions, relative to the logical processor’s home node, and includes these columns:

• home — Indicates the number of times this logical processor was dispatched in its home node.
• adj — Indicates the number of times this logical processor was dispatched in the adjacent node.
• far — Indicates the number of times this logical processor was dispatched in a further node.

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🎀 OPTIONS

• -e, --enable — Enable gathering dispatch statistics persistently, and not only when this command is active.
• -d, --disable — Disable gathering dispatch statistics.
• -n, --numeric — Display the values in numbers, rather than percentages.
• -r, --raw — Display the raw values, rather than the delta.
• -h, --help — Display the usage of vcpustat.
• -V, --version — Display the vcpustat version information.
• interval — The interval parameter specifies the amount of time between each report.
• count — The count parameter specifies how many reports will be displayed.

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🦋 NOTES

The preferred invocation of vcpustat is by specifying interval and an optional count to monitor logical processor dispatch dispersions over a desired interval of time. This enables in-kernel gathering of logical processor dispatch dispersions and provides a view of the same at the desired monitoring interval. With this form of invocation, the statistics are only gathered when the program is active, resulting in minimal kernel overhead. Slay, low overhead, we love to see it. 💖

Long-term statistics can be obtained by enabling gathering of statistics in-kernel through the use of the -e option, followed by invocations of vcpustat without any options, or using the -r option to display raw values, rather than the difference in each monitoring interval. This should only be used when long-term statistics are desired and results in additional kernel load.

💀 It is imperative that the statistics be disabled using the -d option once monitoring is complete.

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🍓 FILES

• /proc/powerpc/vcpudispatch_stats

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👑 AUTHOR

Written by Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>.

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mwah 💋 — sign-off deets: source/version Linux · date Mar 2020 · manual tag VCPUSTAT(8). That’s the whole vibe, bestie. 🫶