Implementing GPUs in your virtual desktop environment (for example vGPU or GPU pass-though) allows better use of graphical intensive applications (like Catia, AutoCAD, Photoshop, etc.). These applications have an impact on utilization (CPU, memory, disk I/O) in your infrastructure. Not only the applications will impact your infrastructure, sending the graphical intensive data over the LAN or WAN will at least impact your network and the CPU on the end-point and inside your virtual desktop. In this article I will explain the impact on network level.
HDX 3D Pro
When using either XenApp or XenDesktop, you will be making use of HDX or HDX 3D Pro. HDX 3D Pro uses a CPU-based codec to do deep-compression on the data sent to the end-client. This will decrease the bandwidth needed to send the data from your virtual desktop to your endpoint device. But how much of a difference does HDX 3D Pro make? I did some tests to see the impact of using HDX 3D Pro versus “normal” HDX compression. I ran the Unigine Valley benchmark both with HDX 3D Pro, “normal” HDX and HDX 3D Pro configured to use lossless graphics (configured through Citrix policy) and measured the bandwidth.
HDX 3D Pro vs No HDX 3D Pro
The first comparison is bandwidth used by HDX 3D Pro versus a XenDesktop VM which has “normal” HDX installed. The total downloaded MB over a 3-and-half-minute time frame (Unigine Valley takes about 3,5 minutes to finish) was 595MB for the VM without HDX 3D Pro, versus 309MB for the VM with HDX 3D Pro enabled. This is a reduction of 48% in favor of HDX 3D Pro.
HDX 3D Pro (default) vs HDX 3D Pro lossless
By modifying the Citrix Policies for XenDesktop, HDX 3D Pro can be configured to send out graphical data in lossless mode. This means that the graphics are sent out pixel-perfect. This mode is normally only adviced in for example medical environments where the images on the endpoint device need to be as perfect as can be. Running the Unigine Valley workload transferred a total of 916MB when using HDX 3D Pro in lossless mode, while the default (lossy) HDX 3D Pro transferred 309MB. This is a reduction of 66% in favor of the lossy mode.
While Unigine Valley may not be a perfect example in case of HDX 3D Pro in lossless mode, these number do give you a clear idea of the bandwidth impact of using HDX 3D Pro in lossless mode.
HDX 3D Pro lossless vs No HDX 3D Pro
The next test I did was to compare lossless mode in HDX 3D Pro versus a VM with “normal” HDX. While “normal” HDX will not give you pixel-perfect images like HDX 3D Pro lossless does, HDX does compress the data enough to make a difference. The total download MB’s for “normal” HDX is 595MB, while the lossless mode for HDX 3D Pro downloaded 916MB. This is a 35% difference in favor of “normal” HDX.
CAD Workloads
As stated before, Unigine may not be the best benchmarking tool for vGPU use in virtual desktop environments. I did test the RedWay Turbine to see the impact of CAD-like applications. Unfortunately I could not get the RedWay Turbine Demo working on the VM without HDX 3D Pro, so I only could do a comparison of HDX 3D Pro lossy vs HDX 3D Pro lossless. In this case the downloaded MB with HDX 3D Pro in lossy (default) mode was 162MB, while HDX 3D Pro in lossless mode was 516MB. This means a 68% decrease of bandwidth in favor of HDX 3D Pro in lossy mode.
Conclusion
As clearly can be seen in the charts, using HDX 3D Pro (versus “normal” HDX) will decrease bandwidth usage by almost 50%. When using lossless mode in HDX 3D Pro, bandwidth will almost triple. So when using lossless mode, be sure to configure the policies only to be applied to the users that REALLY need lossless. By configuring the HDX 3D Pro policies in a granular way, you will make sure that you won’t over-utilize the network.
Totals
To visualize the difference per test, below is a column chart and the table with data gathered during the tests.
| Test name | Total Downloaded MB | Total Uploaded MB | Average Uploaded MB | Max Uploaded MB/s |
| HDX 3D Pro Lossy – RedWay Turbine | 162.2 | 4.2 | 0.02 | 0.08 |
| HDX 3D Pro Lossless – RedWay Turbine | 515.7 | 13.3 | 0.06 | 0.13 |
| HDX 3D Pro Lossy – Unigine Valley | 309.2 | 8.2 | 0.04 | 0.07 |
| HDX 3D Pro Lossless – Unigine Valley | 916.4 | 23.6 | 0.1 | 0.14 |
| No HDX 3D Pro – Unigine Valley | 594.8 | 16 | 0.07 | 0.13 |
I hope this article was usefull for you, if you have any questions or remarks, leave a comment or feel free to send me an email. Be sure to check back soon, I will be adding more articles about the impact on the infrastructure of using HDX 3D Pro.