Real Memory Consumption = Total – (free + buffers + cached)

# free -m


             total       used       free     shared    buffers     cached
Mem:         15943      15678        265          6        511       3706
-/+ buffers/cache:      11460       4483
Swap:         8159          0       8159


# cat /proc/meminfo|grep -i huge

AnonHugePages:         0 kB
HugePages_Total:    4916
HugePages_Free:     3413
HugePages_Rsvd:       35
HugePages_Surp:        0
Hugepagesize:       2048 kB


The total memory reserved for huge pages is approximately 10 G ((4916 * 2048) /1024/1024)
This is approximately equal to 'used' on the second line of the 'free -m' command 11460/1024 = 11G

On an Oracle database server, the Huge Pages should be about 70-80% of the physical RAM  - varies with size, not a hard rule.

On an Oracle database server, the ulimits for the oracle user should be set accordingly - this means that the Oracle user
hard and soft limits for memory should be set high enough

Following files are modified to enable Huge Pages and disable transparent huge pages

/etc/grub.conf	
kernel …… transparent_hugepage=never
--> reboot

Example:
8G RAM --> set 70% for Huge Pages = 5.6G --> set vm.nr_hugepages=2688 in /etc/sysctl.conf --> 5.55G HugePages

--> 2 databases with SGA_TARGET set to 2.6G or 1 database with SGA_TARGET set to 5.5G

MEMORY_TARGET set to 0 (AMM should be disabled when Huge Pages are configured)

/etc/sysctl.conf	
vm.nr_hugepages=2688
(a number representing the number of pages – no unit)
Multiply by 2048 (K) and divide by 1024*1024 to get the number of GB of memory --> 5.55 G in this case

vm.hugetlb_shm_group=3000

/etc/security/limits.conf	
e.g set 7G = 7*1024*1024 = 7340032          --> for a server with 8G of memory

Another example for memlock ulimits:
Set the value (in KB) slightly smaller than installed RAM. e.g. If you have 64GB RAM installed, you may set 
soft memlock 60397977
hard memlock 60397977
(works out to 57G)