System Details - OS Test

This test collects various metrics pertaining to the CPU and memory usage of every processor supported by a Linux system.

Target of the test : A Linux Systems Group

Agent deploying the test : A remote agent

Outputs of the test : One set of results for every combination of systemname:processor

Configurable parameters for the test
Parameter Description

Test Period

How often should the test be executed.

Host

The nick name of the Linux Systems Group component for which this test is to be configured.

Port

Refers to the port at which the specified host listens to. By default, this is NULL.

Inside View Using

To obtain the 'inside view' of performance of the systems - i.e., to measure the internal performance of the systems - this test uses a light-weight eG VM Agent software deployed on each of the systems. Accordingly, this parameter is by default set to eG VM Agent.

Report By User

This flag is set to No by default. This implies that the Linux systems in environments will always be identified using the system name. In other words, this test will, by default, report measures for every systemname. On the other hand, if you want this test to report the measures for every user on a system, then set this flag to Yes. In such a case, this test will report the measures for every username_on_systemname.

Report Powered OS

By default, this flag is set to Yes, then the 'inside view' tests will report measures for even those Linux systems that do not have any users logged in currently. The systems will be identified by their name and not by the username_on_systemname. On the other hand, if this flag is set to No, then this test will not report measures for those systems to which no users are logged in currently.

Is Cloud VMs?

This flag is set to Yes by default. The value of this flag cannot be changed. This implies that the cloud-based Linux systems in environments will always be identified using the login name of the user. In other words, in cloud environments, this test will, by default, report measures for every username_on_systemname.

Exclude

Specify a comma-separated list of processor names / processor name patterns that you want to exclude from monitoring.

CPU Utilization in Percent

Specify the percentage of time beyond which the test should reveal the detailed diagnosis for the CPU utilization measure. By default, this parameter is set to 25. However, you can override this value as per your requirement.

DD Frequency

Refers to the frequency with which detailed diagnosis measures are to be generated for this test. For instance, if you set to 1:1, it means that detailed measures will be generated every time this test runs, and also every time the test detects a problem.

Detailed Diagnosis

To make diagnosis more efficient and accurate, the eG suite embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option.

The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled:

  • The eG manager license should allow the detailed diagnosis capability

  • Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

CPU utilization

This measurement indicates the percentage of CPU utilized by the processor.

Percent

A high value could signify a CPU bottleneck. The CPU utilization may be high because a few processes are consuming a lot of CPU, or because there are too many processes contending for a limited resource. The detailed diagnosis of this test reveals the top-10 CPU-intensive processes on the guest.

System usage of CPU

Indicates the percentage of CPU time spent for system-level processing.

Percent

An unusually high value indicates a problem and may be due to too many system-level tasks executing simultaneously.

Run queue in system

Indicates the instantaneous length of the queue in which threads are waiting for the processor cycle. This length does not include the threads that are currently being executed.

Number

A value consistently greater than 2 indicates that many processes could be simultaneously contending for the processor.

Blocked processes in system

Indicates the number of processes blocked for I/O, paging, etc.

Number

A high value could indicate an I/O problem on the guest (e.g., a slow disk).

Swap memory in system

Indicates the committed amount of memory. This corresponds to the space reserved for memory on disk paging file(s).

MB

An unusually high value for the swap usage can indicate a memory bottleneck. Check the memory utilization of individual processes to figure out the process(es) that has (have) maximum memory consumption and look to tune their memory usages and allocations accordingly.

Free memory in system

Indicates the free memory available.

MB

This measure typically indicates the amount of memory available for use by applications running on the target VM.

On Unix operating systems (AIX and Linux), the operating system tends to use parts of the available memory for caching files, objects, etc. When applications require additional memory, this is released from the operating system cache. Hence, to understand the true free memory that is available to applications, the eG agent reports the sum of the free physical memory and the operating system cache memory size as the value of the Free memory in VM measure while monitoring AIX and Linux guest operating systems.   

Scan rate in system

Indicates the memory scan rate.

Pages/Sec

A high value is indicative of memory thrashing. Excessive thrashing can be detrimental to guest performance.

Note:

  • For multi-processor systems, where the CPU statistics are reported for each processor on the system, the statistics that are system-specific (e.g., run queue length, free memory, etc.) are only reported for the "Summary" descriptor of this test.

  • By default, the Exclude parameter is specified with the value *processor* which indicates that this test will not report metrics for each processor on the system and the metrics will be reported only for the Summary descriptor. If you want this test to report metrics for all the processors on the system, then specify None against the Exclude parameter. In addition, you can also specify the comma-separated list of processors for which you want this test to report metrics against the Exclude parameter.

The detailed diagnosis capability of the CPU utilization measure, if enabled, provides a listing of the top 10 CPU-consuming processes (see Figure 1). In the event of a CPU bottleneck, this information will enable users to identify the processes consuming a high percentage of CPU time. The users may then decide to stop such processes, so as to release the CPU resource for more important processing purposes.

DD Revealing Top 10 CPU Consuming Processes

Figure 1 : The top 10 CPU consuming processes

Note:

While instantaneous spikes in CPU utilization are captured by the eG agents and displayed in the Measures page, the detailed diagnosis will not capture/display such instantaneous spikes. Instead, detailed diagnosis will display only a consistent increase in CPU utilization observed over a period of time.