To lock the SGA into physical memory you have to set the lock_sga parameter to true.
Usually you get following Error message.
SQL> ORA-27102: out of memory
Linux-x86_64 Error: 12: Cannot allocate memory
The problem it ulimit -l
You have to set it in /etc/security/limits.conf and relogon to the system and restart database.
oracle soft memlock unlimited
oracle hard memlock unlimited
alter system set lock_sga=true scope=spfile;
And you SGA stays in physical memory.
If you SGA gets pages out you will encounter following waits.
Wait Event: latch: shared pool