loads.bt(8) System Manager's Manual loads.bt(8)
NAME
loads.bt - Prints load averages. Uses bpftrace/eBPF.
SYNOPSIS
loads.bt
DESCRIPTION
These are the same load averages printed by "uptime", but to three dec-
imal places instead of two (not that it really matters). This is really
a demonstration of fetching and processing a kernel structure from bpf-
trace.
Since this uses BPF, only the root user can use this tool.
REQUIREMENTS
CONFIG_BPF and bpftrace.
EXAMPLES
Print system load averages every second:
# loads.bt
FIELDS
HH:MM:SS
Each output line includes time of printing in "HH:MM:SS" format.
load averages:
These are exponentially-damped moving sum averages of the system
loads. Load is a measurement of demand on system resources,
which include CPUs and other resources that are accessed with
the kernel in an uninterruptible state (TASK_UNINTERRUPTIBLE),
which includes types of disk I/O and lock accesses. Linux load
averages originally reflected CPU demand only, as it does in
other OSes, but this was changed in Linux 0.99.14. This demand
measurement reflects not just the utilized resource, but also
the queued demand (a saturation measurement). Finally, the three
numbers are called the "one-", "five-", and "fifteen-minute"
load averages, however these times are constants used in the ex-
ponentially-damping equation, and the load averages reflect load
beyond these times. Were you expecting an accurate description
of load averages in the man page of a bpftrace tool?
OVERHEAD
Other than bpftrace startup time, negligible.
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.
REFERENCE
For more on load averages, see:
http://www.brendangregg.com/blog/2017-08-08/linux-load-averages.html
OS
Linux
STABILITY
Unstable - in development.
AUTHOR
Brendan Gregg
SEE ALSO
uptime(1)
USER COMMANDS 2018-09-10 loads.bt(8)
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