[Single node DevStack with: Keystone, Glance, Nova, Neutron and Cinder.]

$ sudo ps_mem
Private  +   Shared  =  RAM used	Program 

152.0 KiB +  30.5 KiB = 182.5 KiB	agetty
128.0 KiB +  60.0 KiB = 188.0 KiB	tee
128.0 KiB + 162.0 KiB = 290.0 KiB	inet_gethost (2)
200.0 KiB + 101.0 KiB = 301.0 KiB	tail (2)
108.0 KiB + 200.0 KiB = 308.0 KiB	radvd (2)
372.0 KiB + 107.5 KiB = 479.5 KiB	mysqld_safe
408.0 KiB +  74.0 KiB = 482.0 KiB	epmd
588.0 KiB +  97.0 KiB = 685.0 KiB	auditd
604.0 KiB + 120.5 KiB = 724.5 KiB	dnsmasq
696.0 KiB +  86.0 KiB = 782.0 KiB	crond
796.0 KiB +  58.5 KiB = 854.5 KiB	systemd-logind
732.0 KiB + 242.0 KiB = 974.0 KiB	login
896.0 KiB + 202.5 KiB =   1.1 MiB	tgtd
  1.0 MiB +  96.0 KiB =   1.1 MiB	ovsdb-client
  1.0 MiB + 120.0 KiB =   1.2 MiB	dbus-daemon
664.0 KiB + 609.5 KiB =   1.2 MiB	ovsdb-server
476.0 KiB +   1.1 MiB =   1.6 MiB	monitor (2)
  1.2 MiB + 460.0 KiB =   1.6 MiB	su (2)
992.0 KiB + 995.0 KiB =   1.9 MiB	(sd-pam)
  1.6 MiB + 478.5 KiB =   2.1 MiB	lvmetad
  2.7 MiB + 411.5 KiB =   3.1 MiB	systemd-udevd
  2.1 MiB +   1.1 MiB =   3.2 MiB	sshd (2)
  3.2 MiB + 863.5 KiB =   4.1 MiB	ModemManager
  1.5 MiB +   2.8 MiB =   4.3 MiB	systemd (2)
  5.0 MiB + 113.0 KiB =   5.1 MiB	dstat
  5.8 MiB +  52.0 KiB =   5.8 MiB	screen
  4.9 MiB +   1.3 MiB =   6.2 MiB	NetworkManager
  5.3 MiB +   1.9 MiB =   7.3 MiB	sudo (7)
  7.1 MiB + 810.0 KiB =   7.9 MiB	polkitd
 14.0 MiB + 254.0 KiB =  14.2 MiB	dhclient
  7.7 MiB +   7.1 MiB =  14.9 MiB	systemd-journald
 13.4 MiB +   1.8 MiB =  15.2 MiB	bash (23)
 14.6 MiB +   3.9 MiB =  18.5 MiB	libvirtd
 26.6 MiB + 896.0 KiB =  27.4 MiB	neutron-rootwra (4)
 27.8 MiB + 872.0 KiB =  28.7 MiB	ovs-vswitchd
 42.1 MiB + 215.5 KiB =  42.3 MiB	beam
 49.4 MiB + 221.0 KiB =  49.6 MiB	neutron-ns-meta
 70.2 MiB + 590.0 KiB =  70.7 MiB	cinder-backup
 70.2 MiB + 579.0 KiB =  70.8 MiB	cinder-schedule
 35.8 MiB +  49.8 MiB =  85.6 MiB	cinder-volume (2)
 90.5 MiB +   1.1 MiB =  91.6 MiB	nova-scheduler
 88.2 MiB +   3.6 MiB =  91.8 MiB	nova-compute
 97.6 MiB +   1.1 MiB =  98.7 MiB	nova-conductor
 23.9 MiB + 112.5 MiB = 136.4 MiB	glance-api (3)
 70.5 MiB +  86.7 MiB = 157.2 MiB	glance-registry (3)
181.8 MiB + 385.5 KiB = 182.2 MiB	mysqld
 72.2 MiB + 118.7 MiB = 190.9 MiB	nova-api (5)
164.3 MiB +  27.3 MiB = 191.6 MiB	cinder-api (3)
268.5 MiB +  30.1 MiB = 298.7 MiB	python2.7 (5)
774.5 MiB +  13.1 MiB = 787.6 MiB	httpd (20)
---------------------------------
                          2.7 GiB
=================================