Optimization of Oracle Kernel Parameters in Linux

Database performance optimization involves all aspects of the entire database operating environment, such as the operating system, Oracle itself, storage, and network. The operating system is the cornerstone of Oracle's stable operation and maximum performance. This article mainly describes the configuration of Oracle Kernel Parameters Based on Linux.

Verify that the value of the Kernel Parameter displayed in the list below is set to greater than or equal to the minimum value shown below.

If the current value of any parameter in your system is greater than or higher than the value listed below, do not modify it.

 

The following steps show how to verify and set the values of these parameters.

Run the following command for verification:

/Sbin/sysctl-a | egrep "kernel. shmall | kernel. shmmax | kernel. shmmn | kernel. sem"

Then compare the values listed in the following table

Note: The following table shows the minimum Kernel Parameters and shell restrictions. For production databases, it is recommended that Oracle adjust these values to optimize database performance. For more information about Kernel optimization parameters, see the relevant operating system documentation.

 

Oracle Kernel Parameter reference value

Parameter	Minimum Value	Recommended value	File
Semmsl Semmns Semopm Semmni	250 32000 100 128	Set only if those that are set by OS or other applications are lower	/Proc/sys/kernel/sem
Shmall	2097152	Shmmax/page_size Usually page_size = 4	/Proc/sys/kernel/shmall
Shmmax	Minimum of the following values: · Half the size of the memory · 4 GB-1 byte Note: The minimum value required for shmmax is 0.5 GB. However, Oracle recommends that you set the value of shmmax to 2.0 GB for optimum performance of the system.	Half of RAM or if swap file is less then half of RAM the size of swap file	/Proc/sys/kernel/shmmax
Shmmni	4096	/Proc/sys/kernel/shmmni
File-max	512 * PROCESSES	/Proc/sys/fs/file-max
Ip_local_port_range	Minimum: 9000 # Maximum: 65000	/Proc/sys/net/ipv4/ip_local_port_range
Rmem_default	262144	/Proc/sys/net/core/rmem_default
Rmem_max	4194304	/Proc/sys/net/core/rmem_max
Wmem_default	262144	/Proc/sys/net/core/wmem_default
Wmem_max	1048576	/Proc/sys/net/core/wmem_max
Tcp_wmem	262144	/Proc/sys/net/ipv4/tcp_wmem
Tcp_rmem	4194304	/Proc/sys/net/ipv4/tcp_rmem

 

Verify Kernel Parameters

Follow these steps to view the value of a specified parameter and modify it if necessary.

Run the corresponding commands in the following table to display the value of these kernel parameters, and Mark whether the value of this parameter needs to be modified.

Parameter	Command
Semmsl, semmns, semopm, and semmni	#/Sbin/sysctl-a | grep sem This command displays the value of the semaphore parameters in the order listed.
Shmall, shmmax, and shmmni	#/Sbin/sysctl-a | grep shm This command displays the details of the shared memory segment sizes.
File-max	#/Sbin/sysctl-a | grep file-max This command displays the maximum number of file handles.
Ip_local_port_range	#/Sbin/sysctl-a | grep ip_local_port_range This command displays a range of port numbers.
Rmem_default	#/Sbin/sysctl-a | grep rmem_default
Rmem_max	#/Sbin/sysctl-a | grep rmem_max
Wmem_default	#/Sbin/sysctl-a | grep wmem_default
Wmem_max	#/Sbin/sysctl-a | grep wmem_max
Tcp_wmem	#/Sbin/sysctl-a | grep tcp_wmem
Tcp_rmem	#/Sbin/sysctl-a | grep tcp_rmem

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