#!/usr/bin/env python3
#
# ksm
#
# Plugin to monitor ksm - Kernel Samepage Merging.
#
# Author: Markus Heberling <markus@tisoft.de>
#
# v1.0 2011-04-05 - First version
#
# Usage: place in /etc/munin/plugins/ (or link it there using ln -s)
#
# Parameters understood:
#
#       config   (required)
#       autoconf (optional - used by munin-config)
#
# Magic markers - optional - used by installation scripts and
# munin-config:
#
#  #%# capabilities=autoconf suggest
#  #%# family=auto

import os
import sys
import warnings  # noqa

#################################
title = 'Kernel Samepage Merging'
#################################


def autoconf():
    if os.path.exists('/sys/kernel/mm/ksm/run'):
        for line in open('/sys/kernel/mm/ksm/run'):
            if line.strip() == '1':
                print('yes')
                break
        else:
            print('no (/sys/kernel/mm/ksm/run does not contain "1")')
    else:
        print('no (/sys/kernel/mm/ksm/run not found)')
    sys.exit(0)


def suggest():
    print('pages_absolute')
    print('pages_relative')
    print('full_scans')
    sys.exit(0)


def config():
    if('ksm_pages_absolute' in sys.argv[0]):
        print('graph_category system')
        print('graph_title %s Pages Absolute' % (title))
        print('graph_order pages_unshared pages_volatile pages_shared pages_sharing')
        print('pages_shared.info how many shared pages are being used')
        print('pages_sharing.info how many more sites are sharing them i.e. how much saved')
        print('pages_unshared.info how many pages unique but repeatedly checked for merging')
        print('pages_volatile.info how many pages changing too fast to be placed in a tree')
        print('pages_shared.label pages_shared')
        print('pages_sharing.label pages_sharing')
        print('pages_unshared.label pages_unshared')
        print('pages_volatile.label pages_volatile')
        print('pages_shared.draw AREASTACK')
        print('pages_sharing.draw AREASTACK')
        print('pages_unshared.draw AREASTACK')
        print('pages_volatile.draw AREASTACK')
    elif('ksm_pages_relative' in sys.argv[0]):
        print('graph_category system')
        print('graph_title %s Pages Relative' % (title))
        print('pages_sharing_shared.info ratio of sharing to shared pages')
        print('pages_unshared_sharing.info ratio of unshared to sharing pages')
        print('pages_sharing_shared.label pages_sharing_shared')
        print('pages_unshared_sharing.label pages_unshared_sharing')
        print('pages_sharing_shared.cdef pages_sharing_shared,100,*')
        print('pages_unshared_sharing.cdef pages_unshared_sharing,100,*')
    elif('ksm_full_scans' in sys.argv[0]):
        print('graph_category system')
        print('graph_title %s Full Scans' % (title))
        print('full_scans.info how many times all mergeable areas have been scanned')
        print('full_scans.label full_scans')
    sys.exit(0)


if len(sys.argv) > 1:
    if sys.argv[1] == 'autoconf':
        autoconf()
    elif sys.argv[1] == 'config':
        config()
    elif sys.argv[1] == 'suggest':
        suggest()
    elif sys.argv[1]:
        print('unknown argument "' + sys.argv[1] + '"')
        sys.exit(1)

pages_shared = int(open('/sys/kernel/mm/ksm/pages_shared').read())
pages_sharing = int(open('/sys/kernel/mm/ksm/pages_sharing').read())
pages_unshared = int(open('/sys/kernel/mm/ksm/pages_unshared').read())
pages_volatile = int(open('/sys/kernel/mm/ksm/pages_volatile').read())
full_scans = int(open('/sys/kernel/mm/ksm/full_scans').read())

if('ksm_pages_absolute' in sys.argv[0]):
    print('pages_shared.value %i' % pages_shared)
    print('pages_sharing.value %i' % pages_sharing)
    print('pages_unshared.value %i' % pages_unshared)
    print('pages_volatile.value %i' % pages_volatile)
elif('ksm_pages_relative' in sys.argv[0]):
    print('pages_sharing_shared.value %f'
          % (float(pages_sharing) / float(pages_shared) if pages_shared > 0 else 0))
    print('pages_unshared_sharing.value %f'
          % (float(pages_unshared) / float(pages_sharing) if pages_sharing > 0 else 0))
elif('ksm_full_scans' in sys.argv[0]):
    print('full_scans.value %i' % full_scans)