Infrastructure Software

Hi,

I'm trying to implement hugepages on OL 5.6 as per note "HugePages on Oracle Linux 64-bit [ID 361468.1]" at;
https://support.oracle.com/CSP/main/article?cmd=show&id=361468.1&type=NOT

Step 4 instructs using the script detailed in note "Shell Script to Calculate Values Recommended Linux HugePages / HugeTLB Configuration [ID 401749.1]" however this script fails on one of the hosts (see output at bottom).

This script uses the output of "ipcs -m" to calculate a hugepages value, and as such I have supplied below the output of this command for two servers which are giving me vastly different results. Another difference between the two servers is that one is currently being used by testers and is under load whereas the system I am attempting to configure (host2) is not being used.

My questions are;
1) should I be using this script or is there a better way?
2) is there a reason for the different behaviour of "ipcs -m" (and the script) on the two servers?

Server A:
[root@host3]# ipcs -m

------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x74006fb8 2883584 root 600 4 0
0x00000000 3244033 root 644 80 2
0x00000000 3276802 root 644 16384 2
0x00000000 3309571 root 644 280 2
0x00000000 3342340 gdm 600 393216 2 dest
0xa3c20e68 3538949 grid 660 4096 0
0x52dabc5c 3801094 oracle 660 4096 0
0xa64f7064 3866631 oracle 660 1612709888 29

[root@host3]#

Server B:
[root@host2]# ipcs -m

------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x74008a8f 2981888 root 600 4 0
0x00000000 3342337 root 644 80 2
0x00000000 3375106 root 644 16384 2
0x00000000 3407875 root 644 280 2
0x00000000 3440644 gdm 600 393216 2 dest
0x6d9f45cc 5177349 grid 660 4096 0
0x51abe670 5570566 oracle 660 4096 0

[root@host2]#



Incidentally another version of the hugepages script is located in the documentation at;
http://download.oracle.com/docs/cd/E11882_01/server.112/e10839/appi_vlm.htm#CACFIHHA

Using thes version results in an output of 1, which I interpreted as a default value which is not realistic for implementation.


Rs' V

ps. here is the output of running the script on each of the two servers

Server A:
[root@host3]# ./hugepages_settings.sh

This script is provided by Doc ID 401749.1 from My Oracle Support
(http://support.oracle.com) where it is intended to compute values for
the recommended HugePages/HugeTLB configuration for the current shared
memory segments. Before proceeding with the execution please make sure
that:
* Oracle Database instance(s) are up and running
* Oracle Database 11g Automatic Memory Management (AMM) is not setup
(See Doc ID 749851.1)
* The shared memory segments can be listed by command:
# ipcs -m

Press Enter to proceed...

Recommended setting: vm.nr_hugepages = 770
[root@host3]#

Server B:
[root@host2]# ./hugepages_settings.sh

This script is provided by Doc ID 401749.1 from My Oracle Support
(http://support.oracle.com) where it is intended to compute values for
the recommended HugePages/HugeTLB configuration for the current shared
memory segments. Before proceeding with the execution please make sure
that:
* Oracle Database instance(s) are up and running
* Oracle Database 11g Automatic Memory Management (AMM) is not setup
(See Doc ID 749851.1)
* The shared memory segments can be listed by command:
# ipcs -m

Press Enter to proceed...

***********
** ERROR **
***********
Sorry! There are not enough total of shared memory segments allocated for
HugePages configuration. HugePages can only be used for shared memory segments
that you can list by command:

# ipcs -m

of a size that can match an Oracle Database SGA. Please make sure that:
* Oracle Database instance is up and running
* Oracle Database 11g Automatic Memory Management (AMM) is not configured
[root@host2]#