Memory Usage - OS Test

Memory shortage on a physical machine can affect the memory allocation to crucial processes that are being executed on the physical machine, which in turn can adversely impact the performance of the applications running on the physical machine. One of the primary reasons for Memory shortage is that of precious memory space being unnecessarily hogged by Modified and Standby memory lists that hold temporary/unused data. The Modified and Standby memory lists cache temporary data when the applications/services run in the physical machine. These temporary data will no longer be used by the applications/services thus hogging memory space unnecessarily. Therefore, administrators should clear the cached data on a regular basis. If the cached data is not cleared regularly, sometimes, you may not be able to allocate memory to the business-critical processes, which will seriously impact service/application delivery and impair user experience. Therefore, it is imperative that you should closely observe if the memory shortage occurs due to data growth of the Modified and Standby memory lists and proactively initiate remedial actions before it causes severe memory contention on the physical machine. This can be achieved with the help of the Memory Usage - OS test.

This test auto discovers the physical machines on the server and periodically monitors the memory usage of each physical machine, checks whether adequate physical memory is available to the physical machine, and if not, promptly alerts users to the same. In the process, the test also reveals the physical machines on which the memory space is abnormally hogged by Modified or Standby memory list. This way, physical machines that experience potential memory contention are brought to your attention. Besides warning you of memory contention that Modified/Standby memory lists can cause, the test also empowers you to avoid probable memory shortage by initiating automated actions. These automated actions can be closely tracked using detailed diagnostics.

Target of the test : An Amazon Cloud Desktop Group

Agent deploying the test : A remote agent

Outputs of the test : One set of results for every user_on_desktop

Configurable parameters for the test
Parameter	Description
Test Period	How often should the test be executed.
Host	The nick name of the Amazon Cloud Desktop 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 desktops - i.e., to measure the internal performance of the cloud-based virtual desktops - this test uses a light-weight eG VM Agent software deployed on each of the desktops. Accordingly, this parameter is by default set to eG VM Agent.
Report Powered OS	If this flag is set to Yes (which is the default setting), then the 'inside view' tests will report measures for even those desktops that do not have any users logged in currently. Such desktops will be identified by their name and not by the username_on_desktopname. On the other hand, if this flag is set to No, then this test will not report measures for those desktops to which no users are logged in currently.
Report By User	This flag is set to Yes by default. The value of this flag cannot be changed. This implies that the cloud-based virtual desktops 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_desktopname.
IsCloudVMs	Since this test runs for a 'Amazon Cloud Desktop Group' component, this flag is set to Yes, by default.
Group Processes with Arguments	By default, the detailed diagnosis of the Used physical memory measure of this test reports the number of instances of each process running on the physical machine, and the aggregated memory usage (in MB and %) of every process across all its instances. For example, if users to a physical machine are together having 15 instances of Chrome open on the machine at around the same time, then the detailed diagnosis of the Used physical memory measure will compute and display the collective memory usage of all 15 instances against the Application Name, Chrome. From this, you can quickly identify the exact process that is 'collectively' (i.e., across its instances) over-utilizing the memory. Sometimes, administrators might want to isolate not just the process, but also similar process arguments that are guilty of abnormal memory consumption. This granular insight will take administrators closer to the root-cause of the memory bottleneck on a desktop. For instance, in the Chrome example above, say 8 of the 15 instances are used to access the same YouTube video, and 7 instances are accessing a shopping site. In such a case, if memory usage is aggregated at the URL-level and not the process-level, then administrators can quickly identify which precise URL is draining memory - the YouTube video? or the shopping site? For this, detailed diagnostics should be grouped by process arguments (eg., URLs) and not just by process/application names. To enable grouping by arguments, set the Group Processes With Arguments flag to Yes. By default, this flag is set to No.
Memory Utilization in Percent	By default, this parameter is set to 75 percentage indicating that by default this test will display top-10 memory intensive processes on a physical machine in the detailed diagnosis of the Physical memory utilized measure only when the memory utilization reaches/exceeds 75 percentage. On the other hand, if the memory utilization is lower than the value specified against this parameter, then, this test displays only top-3 memory intensive processes in the detailed diagnosis of the Physical memory utilized measure so as to conserve storage space on the database. However, this setting can be overridden if required.
Automated Action Enabled	A memory shortage caused due to memory space hogged by modified and standby memory lists has become an increasingly frequent and critical problem. The memory shortage can make a server stutter or run more slowly than usual. Such operational interruptions can make you spend more time on waiting for pages and programs to load, disturbing your work flow and leading to work delays. Moreover, memory shortage can not only impair user productivity, but can also bring crucial business processes to a halt, and can severely degrade overall user experience with the server. To avoid such an outcome, administrators need to rapidly empty the memory space unnecessarily hogged by the modified and standby memory lists. This way, administrators can ensure that adequate memory is always available for executing business-critical processes. To enable administrators to achieve this, eG Enterprise offers 'Automation Actions'. These actions are governed by the 'Automation Action Enabled' flag. This flag, if enabled, automatically initiates user-configured actions, so that the memory hogged by modified and standby memory lists can be cleared when memory utilization crosses a configured limit. Note: The 'Automation Action Enabled' parameters, once configured, will apply only to the chosen component. These settings will not be applied to other components even if the Apply to other components button is clicked in the Specific Test Configuration page.
Automation Memory Limit	This flag appears only if the Automated Action Enabled flag is enabled. In this text box, specify the upper limit for memory utilization in percentage beyond which this test should trigger user-configured automation actions. By default, 95 percentage is set against this parameter. When the memory utilization reaches/exceeds the value specified in this text box, the user-configured actions will be automatically triggered. However, you can override this settings if required.
Empty Modified Memory	This flag appears only if the Automated Action Enabled flag is enabled. Modified memory contains cached data and code that is not actively in use by processes, the system and the system cache. This memory needs to be written out before it will be available for allocation to a process or for system use. You can easily clear this memory using the Empty Modified Memory flag. By default, this flag is set to No. When this flag is set Yes, amount of memory assigned to the modified list will be automatically cleared if the memory utilization reaches/exceeds the value specified against the Automation Memory Limit parameter.
Empty Standby Memory	This flag appears only if the Automated Action Enabled flag is enabled. Standby memory is a page of physical memory that is not actively used. When writing a series of frequently used information in the memory area, the programs and services running on the server will use part of memory as cache. The cache should be released and made available after executing programs and services. If the standby memory is not cleared on a regular basis, it can slow down the server operations. Therefore, it is necessary to clear the standby memory at regular intervals. This can easily done using the Empty Standby Memory flag. By default, this flag is set to No. When this flag is set Yes, memory that is allocated to the standby page list will be automatically cleared if the memory utilization reaches/exceeds the value specified against the Automation Memory Limit parameter.
Detailed Diagnosis	To make diagnosis more efficient and accurate, the eG Enterprise 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

Total memory

Indicates the total physical memory of this physical machine.

Used memory

Indicates the used physical memory of this physical machine.

Free memory

Indicates the free physical memory of the physical machine.

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

Memory utilized

Indicates the percent usage of physical memory by this physical machine.

Percent

Ideally, the value of this measure should be low. While sporadic spikes in memory usage could be caused by one/more rogue processes on the physical machine, a consistent increase in this value could be a cause for some serious concern, as it indicates a gradual, but steady erosion of valuable memory resources. If this unhealthy trend is not repaired soon, it could severely hamper physical machine performance, causing anything from a slowdown to a complete system meltdown.

You can use the detailed diagnosis of this measure to figure out which processes on the physical machine are consuming memory excessively.

Available physical memory

Indicates the amount of physical memory, immediately available for allocation to a process or for system use.

Not all of the Available physical memoryis Free physical memory. Typically, Available physical memoryis made up of the Standby List, Free List, and Zeroed List.

When Windows wants to trim a process' working set, the trimmed pages are moved (usually) to the Standby List. From here, they can be brought back to life in the working set with only a soft page fault (much faster than a hard fault, which would have to talk to the disk). If a page stays in the standby List for a long time, it gets freed and moved to the Free List.

In the background, there is a low priority thread (actually, the only thread with priority 0) which takes pages from the Free List and zeros them out. Because of this, there is usually very little in the Free List.

All new allocations always come from the Zeroed List, which is memory pages that have been overwritten with zeros. This is a standard part of the OS' cross-process security, to prevent any process ever seeing data from another. If the Zeroed List is empty, Free List memory is zeroed and used or, if that is empty too, Standby List memory is freed, zeroed, and used. It is because all three can be used with so little effort that they are all counted as "available".

A high value is typically desired for this measure.

Modified memory

Indicates the amount of memory that is allocated to the modified page list.

This memory contains cached data and code that is not actively in use by processes, the system and the system cache. This memory needs to be written out before it will be available for allocation to a process or for system use.

Cache pages on the modified list have been altered in memory. No process has specifically asked for this data to be in memory, it is merely there as a consequence of caching. Therefore it can be written to disk at any time (not to the page file, but to its original file location) and reused. However, since this involves I/O, it is not considered to be Available physical memory.

Standby memory

Indicates the amount of memory assigned to the standby list.

This memory contains cached data and code that is not actively in use by processes, the system and the system cache. It is immediately available for allocation to a process or for system use. If the system runs out of available free and zero memory, memory on lower priority standby cache page lists will be repurposed before memory on higher priority standby cache page lists.

Typically, Standby memory is the aggregate of Standby Cache Core Bytes,Standby Cache Normal Priority Bytes, and Standby Cache Reserve Bytes. Standby Cache Core Bytes is the amount of physical memory, that is assigned to the core standby cache page lists. Standby Cache Normal Priority Bytes is the amount of physical memory, that is assigned to the normal priority standby cache page lists. Standby Cache Reserve Bytes is the amount of physical memory, that is assigned to the reserve standby cache page lists.

Cached memory

This measure is an aggregate of Standby memory and Modified memory.

Automatic action status

Indicates the current status of automatic action.

The values that this measure can report and their corresponding numeric values are discussed in the table above:

Measure value	Numeric value
Not Required	1
Started	2
Running	3
Completed	4
Not Enabled	5
Failed	6

Note:

By default, this measure reports the Measure Values listed in the table above. In the graph of this measure however, the value of this measure is represented using their numeric equivalents only.

Use the detailed diagnosis of this measure to find out what are the automation actions triggered when the memory utilization exceeds the value specified against the Automation Memory Limit parameter.