#!/usr/bin/perl -w
#
# Plugin to monitor memory usage.
#
# Origional Author: Jimmy Olsen
# Contributors:
# Mike Fedyk: Slab, SwapCached, PageTables, VmallocUsed, Mapped, Active, Inactive, 2.4 Rmap & 2.6
#
# Parameters:
#
# 	config   (required)
# 	autoconf (optional - only used by munin-config)
#
# Magic markers (optional - only used by munin-config and some
# installation scripts):
#%# family=auto
#%# capabilities=autoconf


if ($ARGV[0] and $ARGV[0] eq "autoconf")
{
	if (-r "/proc/meminfo")
	{
		print "yes\n";
		exit 0;
	}
	else
	{
		print "/proc/meminfo not found\n";
		exit 1;
	}
}

my %mems;
&fetch_meminfo;

if ($ARGV[0] and $ARGV[0] eq "config")
{
	print "graph_args --base 1024 -l 0 --vertical-label Bytes --upper-limit ", $mems{'MemTotal'}, "\n";
	print "graph_title Memory usage\n";
	print "graph_category system\n";
	print "graph_info This graph shows what the machine uses its memory for.\n";
	print "graph_order ",
		"apps ";
		if (exists $mems{'PageTables'})
		{
			print "page_tables ";
		}
		if (exists $mems{'SwapCached'})
		{
			print "swap_cache ";
		}
		if (exists $mems{'VmallocUsed'})
		{
			print "vmalloc_used ";
		}
		if (exists $mems{'Slab'})
		{
			print "slab ";
		}
		print "cached ",
		"buffers ",
		"free ",
		"swap ",
		"\n";
	print "apps.label apps\n";
	print "apps.draw AREA\n";
	print "apps.info Memory used by user-space applications.\n";
	print "buffers.label buffers\n";
	print "buffers.draw STACK\n";
	print "buffers.info Block device (e.g. harddisk) cache. Also where \"dirty\" blocks are stored until written.\n";
	print "swap.label swap\n";
	print "swap.draw STACK\n";
	print "swap.info Swap space used.\n";
	print "cached.label cache\n";
	print "cached.draw STACK\n";
	print "cached.info Parked file data (file content) cache.\n";
	print "free.label unused\n";
	print "free.draw STACK\n";
	print "free.info Wasted memory. Memory that is not used for anything at all.\n";
	if (exists $mems{'Slab'})
	{
		print "slab.label slab_cache\n";
		print "slab.draw STACK\n";
		print "slab.info Memory used by the kernel (major users are caches like inode, dentry, etc).\n";
	}
	if (exists $mems{'SwapCached'})
	{
		print "swap_cache.label swap_cache\n";
		print "swap_cache.draw STACK\n";
		print "swap_cache.info A piece of memory that keeps track of pages that have been fetched from swap but not yet been modified.\n";
	}
	if (exists $mems{'PageTables'})
	{
		print "page_tables.label page_tables\n";
		print "page_tables.draw STACK\n";
		print "page_tables.info Memory used to map between virtual and physical memory addresses.\n"
	}
	if (exists $mems{'VmallocUsed'})
	{
		print "vmalloc_used.label vmalloc_used\n";
		print "vmalloc_used.draw STACK\n";
		print "vmalloc_used.info Virtual memory used by the kernel (used when the memory does not have to be physically contiguous).\n";
	}
	if (exists $mems{'Committed_AS'})
	{
		print "committed.label committed\n";
		print "committed.draw LINE2\n";
		# Linux machines frequently overcommit - this is not a
		# error condition or even worrying.  But sometimes
		# overcommit shows memory leaks so we want to graph
		# it.
		# print "committed.warning ", $mems{'SwapTotal'} + $mems{'MemTotal'}, "\n";
		print "committed.info The amount of memory allocated by the kernel to programs. Overcommitting is normal, but may indicate memory leaks.\n";
	}
	if (exists $mems{'Mapped'})
	{
		print "mapped.label mapped\n";
		print "mapped.draw LINE2\n";
		print "mapped.info All mmap()ed pages.\n";
	}
	if (exists $mems{'Active'})
	{
		print "active.label active\n";
		print "active.draw LINE2\n";
		print "active.info Memory recently used. Not reclaimed unless absolutely necessary.\n";
	}
	if (exists $mems{'ActiveAnon'})
	{
		print "active_anon.label active_anon\n";
		print "active_anon.draw LINE1\n";
	}
	if (exists $mems{'ActiveCache'})
	{
		print "active_cache.label active_cache\n";
		print "active_cache.draw LINE1\n";
	}
	if (exists $mems{'Inactive'})
	{
		print "inactive.label inactive\n";
		print "inactive.draw LINE2\n";
		print "inactive.info Memory not currently used.\n";
	}
	if (exists $mems{'Inact_dirty'})
	{
		print "inact_dirty.label inactive_dirty\n";
		print "inact_dirty.draw LINE1\n";
		print "inact_dirty.info Memory not currently used, but in need of being written to disk.\n";
	}
	if (exists $mems{'Inact_laundry'})
	{
		print "inact_laundry.label inactive_laundry\n";
		print "inact_laundry.draw LINE1\n";
	}
	if (exists $mems{'Inact_clean'})
	{
		print "inact_clean.label inactive_clean\n";
		print "inact_clean.draw LINE1\n";
		print "inact_clean.info Memory not currently used.\n";
	}
	exit 0;
}

# Any optional value needs to be initialized to zero if it's used in a calculation below
# and is has not been set by &fetch_meminfo

if (exists $mems{'Slab'})
{
	print "slab.value ", $mems{'Slab'}, "\n";
}
else
{
	$mems{'Slab'} = 0;
}
if (exists $mems{'SwapCached'})
{
	print "swap_cache.value ", $mems{'SwapCached'}, "\n";
}
else
{
	$mems{'SwapCached'} = 0;
}
if (exists $mems{'PageTables'})
{
	print "page_tables.value ", $mems{'PageTables'}, "\n";
}
else
{
	$mems{'PageTables'} = 0;
}
if (exists $mems{'VmallocUsed'})
{
	print "vmalloc_used.value ", $mems{'VmallocUsed'}, "\n";
}
else
{
	$mems{'VmallocUsed'} = 0;
}

print "apps.value ", $mems{'MemTotal'}
	-$mems{'MemFree'}
	-$mems{'Buffers'}
	-$mems{'Cached'}
	-$mems{'SwapCached'}
	-$mems{'Slab'}
	-$mems{'PageTables'}
	-$mems{'VmallocUsed'}
	,"\n";
print "free.value ", $mems{'MemFree'}, "\n";
print "buffers.value ", $mems{'Buffers'}, "\n";
print "cached.value ", $mems{'Cached'}, "\n";
print "swap.value ", $mems{'SwapTotal'} - $mems{'SwapFree'}, "\n";

if (exists $mems{'Committed_AS'})
{
	print "committed.value ", $mems{'Committed_AS'}, "\n";
}
if (exists $mems{'Mapped'})
{
	print "mapped.value ", $mems{'Mapped'}, "\n";
}
if (exists $mems{'Active'})
{
	print "active.value ", $mems{'Active'}, "\n";
}
if (exists $mems{'ActiveAnon'})
{
	print "active_anon.value ", $mems{'ActiveAnon'}, "\n";
}
if (exists $mems{'ActiveCache'})
{
	print "active_cache.value ", $mems{'ActiveCache'}, "\n";
}
if (exists $mems{'Inactive'})
{
	print "inactive.value ", $mems{'Inactive'}, "\n";
}
if (exists $mems{'Inact_dirty'})
{
	print "inact_dirty.value ", $mems{'Inact_dirty'}, "\n";
}
if (exists $mems{'Inact_laundry'})
{
	print "inact_laundry.value ", $mems{'Inact_laundry'}, "\n";
}
if (exists $mems{'Inact_clean'})
{
	print "inact_clean.value ", $mems{'Inact_clean'}, "\n";
}

sub fetch_meminfo
{
	open (IN, "/proc/meminfo") || die "Could not open /proc/meminfo for reading: $!";
	while (<IN>)
	{
		if (/^(\w+):\s*(\d+)\s+kb/i)
		{
			$mems{"$1"} = $2 * 1024;
		}
	}
	close (IN);
	# Only 2.6 and above has slab reported in meminfo, so read slabinfo if it isn't in meminfo
	if (!$mems{Slab})
	{
		&fetch_slabinfo;
	}
	# Support 2.4 Rmap VM based kernels
	if (!$mems{'Inactive'} && $mems{'Inact_dirty'} && $mems{'Inact_laundry'} && $mems{'Inact_clean'})
	{
		$mems{'Inactive'} = $mems{'Inact_dirty'} + $mems{'Inact_laundry'} + $mems{'Inact_clean'}
	}
}

sub fetch_slabinfo
{
	# In 2.0 there is no slabinfo file, so return if the file doesn't open
	open (IN, "/proc/slabinfo") || return;
	my @slabinfo;
	my $tot_slab_pages = 0;
	my $slab_version = <IN>;
	if ($slab_version =~ /^slabinfo - version: 1.1/)
	{
		while (<IN>)
		{
			if (!/^slabinfo/)
			{
				@slabinfo = split;
				$tot_slab_pages += $slabinfo[5];
			}
		}
	}
	close (IN);
	if ($tot_slab_pages gt 0)
	{
		$mems{'Slab'} = $tot_slab_pages * 4096;
	}
}

# vim:syntax=perl:ts=8