loads(8) - f36

1loads(8)                    System Manager's Manual                   loads(8)
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NAME

6       loads.bt - Prints load averages. Uses bpftrace/eBPF.
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SYNOPSIS

9       loads.bt
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DESCRIPTION

12       These are the same load averages printed by "uptime", but to three dec‐
13       imal places instead of two (not that it really matters). This is really
14       a demonstration of fetching and processing a kernel structure from bpf‐
15       trace.
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17       Since this uses BPF, only the root user can use this tool.
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REQUIREMENTS

20       CONFIG_BPF and bpftrace.
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EXAMPLES

23       Print system load averages every second:
24              # loads.bt
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FIELDS

27       HH:MM:SS
28              Each output line includes time of printing in "HH:MM:SS" format.
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30       load averages:
31              These are exponentially-damped moving sum averages of the system
32              loads.   Load  is  a  measurement of demand on system resources,
33              which include CPUs and other resources that  are  accessed  with
34              the  kernel  in an uninterruptible state (TASK_UNINTERRUPTIBLE),
35              which includes types of disk I/O and lock accesses.  Linux  load
36              averages  originally  reflected  CPU  demand only, as it does in
37              other OSes, but this was changed in Linux 0.99.14.  This  demand
38              measurement  reflects  not  just the utilized resource, but also
39              the queued demand (a saturation measurement). Finally, the three
40              numbers  are  called  the  "one-", "five-", and "fifteen-minute"
41              load averages, however these times are constants used in the ex‐
42              ponentially-damping equation, and the load averages reflect load
43              beyond these times. Were you expecting an  accurate  description
44              of load averages in the man page of a bpftrace tool?
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OVERHEAD

47       Other than bpftrace startup time, negligible.
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SOURCE

50       This is from bpftrace.
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52              https://github.com/iovisor/bpftrace
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54       Also  look  in  the bpftrace distribution for a companion _examples.txt
55       file containing example usage, output, and commentary for this tool.
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REFERENCE

58       For more on load averages, see:
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60       http://www.brendangregg.com/blog/2017-08-08/linux-load-averages.html
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OS

63       Linux
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STABILITY

66       Unstable - in development.
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AUTHOR

69       Brendan Gregg
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