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 decimal places instead
       of two (not that it really matters). This  is  really  a  demonstration  of  fetching  and
       processing a kernel structure from bpftrace.

       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 exponentially-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)