Its bunch of perl script using RRDTool modules to generate historical graphs.
Drop all files in single folder and configure rrd-conf.pl to set some variables and path. When you run any perl script it will create rrd data directory in local dir.
Add them in cron to run periodically
0-59/5 * * * * /home/spatel/rrd/memory.pl >/dev/null
0-59/5 * * * * /home/spatel/rrd/pmem.pl >/dev/null