#!/usr/bin/sh
# -*- sh -*-

: << =cut

=head1 NAME

interrupts - Plugin to monitor the number of interrupts and context
switches on a system.

=head1 CONFIGURATION

No configuration

=head1 AUTHOR

Idea and base from Ragnar Wisløff.

=head1 LICENSE

GPLv2

=head1 MAGIC MARKERS

 #%# family=auto
 #%# capabilities=autoconf

=cut

. "$MUNIN_LIBDIR/plugins/plugin.sh"

if [ "$1" = "autoconf" ]; then
	if [ -r /proc/stat ]; then
		echo yes
		exit 0
	else
		echo no
		exit 0
	fi
fi

# If run with the "config"-parameter, give out information on how the
# graphs should look.

if [ "$1" = "config" ]; then
	# The title of the graph
	echo 'graph_title Interrupts and context switches'
	# Arguments to "rrdtool graph". In this case, tell it that the
	# lower limit of the graph is '0', and that 1k=1000 (not 1024)
	echo 'graph_args --base 1000 -l 0'
	# The Y-axis label
	# shellcheck disable=SC2016
	echo 'graph_vlabel interrupts & ctx switches / ${graph_period}'
	# Graph category
	echo 'graph_category system'
	# Graph information
	echo 'graph_info This graph shows the number of interrupts and context switches on the system. These are typically high on a busy system.'
	echo 'intr.info Interrupts are events that alter sequence of instructions executed by a processor. They can come from either hardware (exceptions, NMI, IRQ) or software.'
	echo 'ctx.info A context switch occurs when a multitasking operatings system suspends the currently running process, and starts executing another.'
	# The fields. "label" is used in the legend. "label" is the only
	# required subfield.
	echo 'intr.label interrupts'
	echo 'ctx.label context switches'
	# Specify type
	echo 'intr.type DERIVE'
	echo 'ctx.type DERIVE'
	echo 'intr.min 0'
	echo 'ctx.min 0'

	print_warning intr
	print_critical intr
	print_warning ctx
	print_critical ctx

	# Last, if run with the "config"-parameter, quit here (don't
	# display any data)
	exit 0
fi

# The real work

awk '$1 == "intr" { print "intr.value " $2 }
     $1 == "ctxt" { print "ctx.value " $2 }' /proc/stat