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Measures reported by WVDOSMemoryTest
This test reports statistics related to the usage of physical memory of the VMs.
Outputs of the test : One set of results for the chosen session host.
The measures made by this test are as follows:
| Measurement |
Description |
Measurement Unit |
Interpretation |
| Total_phy_mem |
Indicates the total memory at the disposal of the Azure virtual desktop. |
MB |
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| Used_phy_mem |
Indicates the memory used by the Azure virtual desktop. |
MB |
Use the detailed diagnosis of this measure to know which application has the maximum number of instances running and how much memory is used by each application across all its instances. In the event of a memory contention on the desktop, these diagnostics will quickly point you to the process/application that is contributing to the contention. Optionally, you can turn on the Group Processes With Arguments flag and have detailed diagnosis aggregate memory usage by process argument and not process/application name. If this is done, then the detailed metrics will indicate which exact process argument is memory-hungry. |
| Free_phy_mem |
Indicates the unused memory on the Azure virtual desktop. |
MB |
This measure typically indicates the amount of memory available for use by applications running on the target virtual desktop.
For peak application performance therefore, the value of this measure should be high. |
| Physical_mem_utilze |
Indicates the percent of allocated memory that is used by the chosen Azure virtual desktop. |
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 virtual desktop, 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 virtual desktop 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 desktop are consuming memory excessively. |
| Available_phy_mem |
Indicates the amount of memory, immediately available for allocation to a process or for system use. |
MB |
Not all of the Available memory is Free memory. Typically, Available memory is 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_mem |
Indicates the amount of memory that is allocated to the modified page list. |
MB |
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_mem |
Indicates the amount of memory assigned to the standby list. |
MB |
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_mem |
This measure is an aggregate of Standby memory and Modified memory. |
MB |
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