#!/bin/sh
#%# family=auto

: << EOF
=head1 NAME

zswap - Outputs various metrics about [zswap](https://www.kernel.org/doc/html/latest/admin-guide/mm/zswap.html).

=head1 AUTHOR

Michael Grote

=head1 Configuration

This Plugin has to be run as root:

/etc/munin/plugin-conf.d/zswap:

[zswap]

user root


=head1 LICENSE

GPLv3 or later

SPDX-License-Identifier: GPL-3.0-or-later

=head1 MAGIC MARKERS

  #%# family=auto

  #%# capabilities=autoconf

=cut

EOF


# Variables
SYSFS_ZSWAP_DIR="/sys/kernel/debug/zswap"

# Link to Descriptions: https://kruyt.org/telegraf-zswap/
print_labels () {
cat << EOF
graph_title zswap
graph_category system
duplicate_entry.label duplicate entry
pool_limit_hit.label pool limit hit
pool_total_size.label pool total size
reject_alloc_fail.label reject alloc fail
reject_compress_poor.label reject compress poor
reject_kmemcache_fail.label reject kmemcache fail
reject_reclaim_fail.label reject reclaim fail
same_filled_pages.label same filled pages
stored_pages.label stored pages
written_back_pages.label written back pages
duplicate_entry.info
pool_limit_hit.info the zswap pool limit has been reached
pool_total_size.info
reject_alloc_fail.info
reject_compress_poor.info reject pages due to poor compression policy (cumulative) (see max_compressed_page_size sysfs attribute)
reject_kmemcache_fail.info rejected pages due to kmem failure (cumulative)
reject_reclaim_fail.info
same_filled_pages.info "Some of the pages in zswap are same-value filled pages (i.e. contents of the page have same value or repetitive pattern)."
stored_pages.info number of compressed pages stored in zswap
written_back_pages.info
EOF
}



# wenn parameter = ...
if [ "$1" = "autoconf" ]; then
  # check if File contains a "Y"
  if ! grep -q Y "/sys/module/zswap/parameters/enabled"; then
    echo "no (zswap not enabled)"
    exit 0
  fi
  echo yes
  exit 0
fi

if [ "$1" = "config" ]; then
  # setze label
  print_labels
  exit 0
fi

echo duplicate_entry.value "$(cat "$SYSFS_ZSWAP_DIR/duplicate_entry")"
echo pool_limit_hit.value "$(cat "$SYSFS_ZSWAP_DIR/pool_limit_hit")"
echo pool_total_size.value "$(cat "$SYSFS_ZSWAP_DIR/pool_total_size")"
echo reject_alloc_fail.value "$(cat "$SYSFS_ZSWAP_DIR/reject_alloc_fail")"
echo reject_compress_poor.value "$(cat "$SYSFS_ZSWAP_DIR/reject_compress_poor")"
echo reject_kmemcache_fail.value "$(cat "$SYSFS_ZSWAP_DIR/reject_kmemcache_fail")"
echo reject_reclaim_fail.value "$(cat "$SYSFS_ZSWAP_DIR/reject_reclaim_fail")"
echo same_filled_pages.value "$(cat "$SYSFS_ZSWAP_DIR/same_filled_pages")"
echo stored_pages.value "$(cat "$SYSFS_ZSWAP_DIR/stored_pages")"
echo written_back_pages.value "$(cat "$SYSFS_ZSWAP_DIR/written_back_pages")"