The software described in this documentation is either in Extended Support or Sustaining Support. See https://www.oracle.com/us/support/library/enterprise-linux-support-policies-069172.pdf for more information.
Oracle recommends that you upgrade the software described by this documentation as soon as possible.
Many performance issues are the result of configuration errors. You can avoid such errors by using a validated configuration that has been pre-tested fore the supported software, hardware, storage, drivers, and networking components. A validated configuration incorporates the best practices for Oracle Linux deployment and has undergone real-world testing of the complete stack. Oracle publishes more than 100 validated configurations, which are freely available for download. You should also refer to the release notes for recommendations on setting kernel parameters.
A typical problem involves out of memory errors and generally poor performance when running Oracle Database. The cause of this problem is likely to be that the system is not configured to use the HugePages feature for the System Global Area (SGA). With HugePages, you can set the page size to between 2MB and 256MB, so reducing the total number of pages that the kernel needs to manage. The memory associated with HugePages cannot be swapped out, which forces the SGA to remain resident in memory.
The following utilities allow you to collect information about system resource usage and errors, and can help you to identify performance problems caused by overloaded disks, network, memory, or CPUs:
- dmesg
Displays the contents of the kernel ring buffer, which can contain errors about system resource usage. Provided by the
util-linux-ngpackage.- dstat
Displays statistics about system resource usage. Provided by the
dstatpackage.- free
Displays the amount of free and used memory in the system. Provided by the
procpspackage.- iostat
Reports I/O statistics. Provided by the
sysstatpackage.- iotop
Monitors disk and swap I/O on a per-process basis. Provided by the
iotoppackage.- ip
Reports network interface statistics and errors. Provided by the
iproutepackage.- mpstat
Reports processor-related statistics. Provided by the
sysstatpackage.- sar
Reports information about system activity. Provided by the
sysstatpackage.- ss
Reports network interface statistics. Provided by the
iproutepackage.- top
Provides a dynamic real-time view of the tasks that are running on a system. Provided by the
procpspackage.- uptime
Displays the system load averages for the past 1, 5, and 15 minutes. Provided by the
procpspackage.- vmstat
Reports virtual memory statistics. Provided by the
procpspackage.
Many of these utilities provide overlapping functionality. For more information, see the individual manual page for the utility.
See Section 4.2.3, “Parameters that Control System Performance” for a list of kernel parameters that affect system performance.