login vsi company logo login vsi company logo 250x40

Essential VDI Performance Graphs in the Login VSI Analyzer

Essential VDI Performance Graphs in the Login VSI Analyzer

Every user of Login VSI knows the “famous” VSImax chart in the Login VSI Analyzer. This chart is used in almost every VDI white paper of the major software / hardware vendors in our industry and basically shows the maximum capacity of your virtualized desktop environment. Besides VSImax, I frequently notice that many of our customers are not very familiar with the other charts in the Login VSI Analyzer. In this blog I would like to share some charts and features of the Login VSI Analyzer that I frequently use after a performance test.

VSImax v4 Detailed Weighted

The VSImax Graph is calculated based on several metrics. To better understand how the individual metrics influence the overall VSImax result, you will need to take a look at the weighted view. In this graph you will see how each individual metric influences the VSImax score in comparison to the other metrics. For those of you that want to read the full story on VSImax calculation, read the blog by my colleague Jordi with a detailed overview of all the calculations.

In the graph below its easily noticeable that the NSLD (Notepad Start Load) was spiking much more in comparison to the other metrics. This is a good starting point to dig deeper into the bottleneck. The next step is to find out why this NSLD metric is so high. Other graphs and external data can help you with this.

login vsi analyzer vsimax v4 detailed weighted

VSImax v4 detailed weighted graph

The VSImax detailed graph also contains two specific metrics that cannot be found in any other tab: “File Copy To Server” (FCTS) and “File Copy To Local” (FCTL). If the FCTS score is spiking, this could be an indicator that the network is your bottleneck, while FCTL could be an indicator that your local disk is the problem.

Tip: Use the "Select Averages” option by clicking the metric selection overview with your right mouse button. This will remove the maximum and minimum lines and this makes it much easier to see the impact of the different metrics.

login vsi analyzer select averages

Scatter chart

In the main and detailed VSImax charts you only look at the minimum, maximum and average test results. In the scatter chart you can actually see the measurements of all the individual sessions. The scatter chart is very interesting and makes it easy to spot outliers. For example, when a single VM, especially at the beginning of the test, has very high response times while the rest has a lower score, it’s a great indicator that there was a performance problem with an individual session or VM. The scatter chart is also very useful to determine if you need another VSIshare.

login vsi analyzer scatter chart

Scatter chart

NFO

NFO is the file open dialog, so how long does it take to display the file open dialog. This is a really interesting one because if you would redirect the home directory to an H: drive, and you see a huge increase in this graph and all the others basically stay the same, it probably means that you have a problem with the location where the H: drive is hosted.

login vsi analyzer nfo

NFO

CPU

Login VSI calculates the CPU performance by generating a large array of random data and spiking the VM’s CPU for a short period of time. The great thing about this Login VSI activity, is that it’s 100% CPU based. There is no IO required for this measurement, so this is the purest CPU measurement that Login VSI does. If this graph goes up, you probably know that you have a CPU bottleneck, so this graph definitely helps you to isolate where the performance problem is coming from.

login vsi analyzer cpu

CPU

Storage IO

If it’s not CPU and we want to take a look at storage, we can go to the IO tab in the Analyzer. The IO metric is actually not used for the VSImax calculation but we do measure it by writing a couple of random blocks to the %temp% directory of the Login VSI users. This IO measurement is a great way to determine, without external performance data, if the storage that hosts the %temp% directory is the bottleneck.

login vsi analyzer io

IO graph

But the increasing latency of the graph doesn’t tell the complete story of Storage IO vs CPU, because storage latency can be affected by the CPU. If the CPU chart is not increasing but IO latency is dramatically increasing during the test, then you probably have a storage bottleneck. If you see that CPU increases, a logical effect is that IO latency also increases (but it will be much less erratic), which means it’s probably a CPU bottleneck.

In short: if CPU and IO latency both go up, then it’s probably a CPU bottleneck. If only IO latency goes up, it’s most likely a storage bottleneck.

NOTE: The IO score can be impacted by settings in the image. Think for example about your AV solution that is scanning all the files. 

AppStart

Another interesting graph in the Login VSI Analyzer is AppStart. This graph shows the start times of all the applications during a Login VSI test. You can use the AppStart graph to better understand application launches and how this is being influenced by different settings. It’s important to note that AppStart is not a very good indicator to show system saturation (like VSImax) because many times we see that application start times are fast while overall responsiveness of the VM was super sluggish.

login vsi analyzer appstart

AppStart

It’s also interesting to note that you will usually see a high latency value and low latency value for each application. A high latency value is typically seen the first time the application was started within the VM. Once an application has been started and you close it, it will be cached to memory on the Windows VM. The second time an application is started, the latency is much lower. It’s totally normal to have such high differences for the same application. On your own laptop or pc you will see the same behavior. The second time, you launch an app, it’s much quicker.

LogonTimer

The final graph I use on a regular basis is “LogonTimer”. This graph basically shows how long it took from the start of Login VSI’s logon script until the first application has started. In the example screenshot below you can see that the logon time is pretty evenly spread out, as the workload grows, and evenly ranges from 8 to 16 seconds. In typical enterprise environments you will see that login time is not that quick. In the real world I’ve seen a lot of cases where 3 minutes was normal. This is not very user-friendly so you can use the LogonTimer graph to tune and tweak your environment policy settings to see if you can lower your logon time.

login vsi analyzer logontimer

LogonTimer

External data

If you really want to deep-dive into where the performance bottleneck is coming from, you can also import external performance data from the host level (e.g. VMware ESXtop, XenServer or Microsoft Perfmon) data in the Login VSI Analyzer.

In the screenshot below I imported the host total CPU utilization time from ESXtop into the Analyzer. The orange line clearly shows that CPU increases over time to 100% (see the right axis), and that VSImax was hit well before that 100% CPU number. Typically, VSImax is already hit when the CPU is at 80% to 90% VM utilization.

login vsi analyzer external data

External data in the Login VSI Analyzer

You can import your own external data in the Analyzer by going to File > Import and by clicking on External Data. You can use any comma separated text file (CSV) as long as it contains a time stamp and a value.

Below you will find some useful ESXtop metrics (Perfmon and XenServer have similar metrics):

  • Avg % Util
  • Avg % Processor Time
  • %Ready
  • Avg IO Commands/sec
  • Avg IO Reads/sec
  • Avg IO/Writes sec
  • Avg MBytes Read/sec
  • Avg MBytes Write/sec
  • Avg Guest Latency
  • Network Related

NOTE: When using Microsoft Perfmon don’t use the metrics of the host partition, make sure you choose the hypervisor metrics.

Ready to start analyzing some test results?

There is probably a lot more data that you can get out of the Login VSI Analyzer but these are the graphs that I use most often when I analyze results from VDI performance tests for our customers. I hope that this information will help you to better understand your virtualized desktop environment. If you need any help, I am more than happy to help. You can reach me on twitter via @jaspergeelen or drop me an email at j.geelen@loginvsi.com

This blog by my colleague Mark about lesser known tips for your VDI performance tests might also be interesting for you.

Happy VDI performance testing!

About the author

Jasper Geelen (@jaspergeelen) has a background in ICT and joined Login VSI as a pre-sales engineer in 2015. He loves drinking a lot of coffee (some might call him an addict). In his spare time, Jasper enjoys a beer and he is part of a football / soccer team. He also coaches a team of younger football players.


Tags: Login VSI

Popular Blogs

login-vsi-vdi-performance-summit

The VDI Performance Summit - Virtual Conference and Expo

Visit the VDI Performance Summit to gain knowledge and experience about performance and tuning VDI, improving End-User Experience and IT service. Join us at the ONLY virtual event 100% dedicated to VDI performance and tuning | May 2, 2019 This 1-day event offers key-notes presented by the best VDI performance experts in the world, technical and business oriented breakout sessions, the possibility to chat with experts directly to discuss your own situation, and a virtual exhibit hall featuring… Continue Reading

Scalability testing Parallels Remote Application Server with Login VSI

Recently I went to VMworld in Barcelona where Login VSI had a booth on the expo... While I can’t remember exactly how many conversations I had - there had been so many that I lost my voice on day one. What was new this year is that quite a few people asked if our software is compatible with the solutions from Parallels specifically their Remote Application Server (RAS) (Datasheet). Continue Reading
Login VSI Blog Article - Microsoft Windows 10 Default FTA Associations - Teaser Image

Windows 10 Default File Type Associations and Login VSI

When Login VSI 4.1 was released, the majority of desktops were running Windows 7 and life was easy. We’d set the default filetype for an application and it would simply work. The default and industry standard workloads in Login VSI include launching and using Adobe Reader as part of the virtual user simulation. Because Login VSI doesn’t always know which version of Adobe Reader is installed, or where it’s installed, the workload relies on the file type association (FTA) for .pdf documents to be… Continue Reading
Login VSI - Press Release - IGEL - Login VSI Partner to Optimize End User Computing Experience Image

[Press Release] IGEL Partners with Login VSI to Optimize the End User Computing Experience

Login PI enables organizations to better protect the performance and availability of their IGEL OS-powered virtual desktop environments San Francisco, USA, Feb. 6, 2019: IGEL, a world leader in software-defined endpoint optimization and control solutions for the secure enterprise, today announced that it is partnering with Login VSI, provider of software solutions to test and actively monitor the performance and availability of virtual desktop environments, including VDI and… Continue Reading
Login VSI - Blog - Login PI Blog Teaser Image - Windows Virtual Desktop: How To Monitor User Experience With Login PI

Windows Virtual Desktop – How to Monitor User Experience?

Microsoft has just announced the public preview of their new Windows Virtual Desktop (WVD) offering at Microsoft Ignite on Tour in Amsterdam today. For those of you who’ve not followed the rumors or the private beta, here’s the outline... Continue Reading
Investigating Online Application Performance with Login PI

Investigating Online Application Performance with Login PI

As many companies do, we use a CRM system. Recently, I have been getting complaints about our cloud CRM system, Microsoft Dynamics, being slow. I tried to investigate this by shadowing one of our users to see what was wrong. As expected, everything was fast. 15 minutes later, the same user reported slowness again. How could I investigate this without bothering the users? Continue Reading
Cookie Settings