Tags: WEM

Citrix Workspace Environment Management – IO Management

I’ve been blogging a lot this year on the merits of Citrix Workspace Environment Management (WEM) and the various features it provides. Another feature is I/O Priority – which enables us to manage the priority of I/O operations for a specified process:

To demonstrate this, I am going to run IOMeter (a storage testing tool – that consumes, but also measures CPU utilisation during testing), and SuperPi (a tool that calculates Pi to a specified number of digits – and consumes large amounts of CPU during calculation).

Before making any WEM configuration changes, on my virtual desktop the results are as follows:

IOMeter (Using the Atlantis Template – available here) –  shows 6.56% CPU Utilisation, and 3581 I/Os per second:

SuperPI calculation to 512K – 7.1 seconds:

Next I added the IOMeter and SuperPi executables into WEM, and set the priority to very low:

As a result of doing this the IOMeter results are significantly reduced, and the calculation time for SuperPi has increased significantly:

IOMeter Result – around 60% reduction in I/O per second, and 2% CPU usage reduction:

SuperPI – time to calculate has increased by nearly 200%:

From this test – it is clear to see that I/O Management within Workspace Environment Management is an effective way to control the I/O operations of specified processes. Whilst you might think slowing down the performance of an application is unlikely to be a major requirement for many of us – the ability to control particularly resource intensive applications is a definite win for complex environments. If a particular application is causing performance problems (for example degrading the performance for others) then this provides a suitable solution to manage that process.

Citrix Workspace Environment Management – Process Management

After testing out the excellent CPU and Memory management features in Citrix Workspace Environment Management (WEM), I wanted to blog about how processes can be controlled using the software.

Prior to starting this test, I have a basic Citrix XenDesktop environment configured, a WEM environment configured, and the relevant group policies in place to support this.

To prevent processes from running, we browse to System Optimization, and then Process Management:

From here we can enable process management:

Next – we have two options, we can whitelist, or blacklist. If we whitelist – only those executables listed will be allowed to run, whereas a blacklist will block only those listed.

I’m going to test out a blacklist:

We can exclude local administrators, and also choose to exclude specified groups – for example perhaps a trusted subset of users or specific groups of users who need to run some of the applications we wish to block.

For this test I am going to add notepad.exe to the list:

Next I saved the WEM configuration, refreshed the cache, and then logged into a Desktop Session to test the blacklist. Upon firing up notepad I am greeted with the message:

Bingo – a simple and effective way to block processes from running. This would be very effective when combined with a list of known malicious executables for example, or known problematic software items.

In a future release I’d love to see more granularity in this feature – for example blacklists, with the ability to whitelist processes for certain groups, rather than as a whole. This would enable control of applications on a much more granular level – for example, blocking “process.exe” for Domain Users, but allowing it for a trusted group of users.

 

Citrix Workspace Environment Management – Memory Management

After testing out the excellent CPU management features in Citrix Workspace Environment Management (WEM), I wanted to test out how well it handled applications that were particularly greedy with RAM consumption.

To start – I have a single Windows Server 2012R2 Session Host, with 4GB of RAM, and a single vCPU, running on vSphere:

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Limitations for this VM have been individually configured as follows:

RAM:

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CPU:

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I wanted to use limitations to give a performance baseline. Although this is much lower than most Session Hosts would likely be – it will prove the concept for this test.

Next I configured the Session Host with the WEM Agent and imported the default baselines as per Citrix documentation. Within the Console, we can then see the Memory Management options:

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According to the Administration Guide, this enables the following:

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For the purposes of this test, I am going to set the idle limit time to 5 minutes. I will be using TestLimit, a command line tool to simulate high memory usage, available here:

https://blogs.msdn.microsoft.com/vijaysk/2012/10/26/tools-to-simulate-cpu-memory-disk-load/

I’ve configured a batch file that will start TestLimit64.exe, and consume 3.5GB of RAM (from a total of 4GB assigned to the session host).

Prior to any WEM configuration being applied, running this batch file causes Memory Usage to rise as expected:

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This remains until the process is closed manually.

Next, I ran the same process but for a user logged on with active WEM Settings – including Memory Management. Initially we saw the same rise in memory:

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I then waited 5 minutes (the time limit we set earlier), with the application running in the background, and then checked the stats again:

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As you can see the excess memory consumed by this application has been released – and is now available to other processes running on the Session Host. I tested this multiple times on different machines and session hosts, and saw the same result each time.

This potentially very useful for situations where a single user may be using a program that runs periodically, but sits with high RAM consumption in the background. Releasing under-utilized RAM will improve the session experience in the event that RAM capacity is being reached.