$ ls /etc/sysctl.d/		
$ cat /etc/sysctl.d/30-postgresql-shm.conf
			

內存與交換分區分配相關

https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Performance_Tuning_Guide/s-memory-captun.html

vm.overcommit_memory = 1