Don’t let your user-experience be a “Spectre” of itself after “Meltdown” - Login VSI
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    Don’t let your user-experience be a “Spectre” of itself after “Meltdown”

    Bust your ghosts not your user experience

    The names Spectre and Meltdown invoke feelings of dread in even the most seasoned IT engineer. To those uninitiated, let me get you up-to-speed quickly. Spectre is a vulnerability that takes advantage of “Intel Privilege Escalation and Speculative Execution”, and exposes user memory of an application to another malicious application. This can expose data such as passwords. Meltdown is a vulnerability that takes advantage of “Branch prediction and Speculative Execution”, and exposes kernel memory. A compromised server or client OS running virtualized could gain access to kernel memory of the host exposing all guest data. Both vulnerabilities take advantage of a 20-year-old method of increasing processor performance.

    As a result, code will need to be updated to address these vulnerabilities at OS and OEM-manufacturer levels, at the expense of system performance. On their part, Microsoft reluctantly admits that performance will suffer.  “Windows Server on any silicon, especially in any IO-intensive application, shows a more significant performance impact when you enable the mitigations to isolate untrusted code within a Windows Server instance,” wrote Terry Myerson, Executive Vice President for the Windows and Devices group.

    According to Geek Wire, these two vulnerabilities can be “mitigated;” the word we’re apparently using to describe this new world in 2018, in which servers lose roughly 10 to 20% performance for several common workloads. This affects not only workloads executed against local, on-site resources but also those utilizing services, such as AWS, Google Public Cloud or Azure.

    Don’t let your user-experience be a “Spectre” of itself after “Meltdown”Reader submission @ The Register showing CPU before / after patches

    Minimize performance problems by testing patches in advance

    Some of our insiders who use Login VSI to validate system performance see a reduction of 5% in user-density after performing Microsoft recommendations. Knowing that the vulnerability wasn’t solved by OS updates alone we also strongly recommend to test the impending hardware vendor firmware / BIOS changes.

    To establish how much performance impact the fixes for Spectre and Meltdown will have, you must have something to compare it to. Keep in mind that these patches need to be installed on a number of systems in your environment including server hardware, operating systems, storage subsystems and so on.

    Our customers perform tests where they compare a known good solution, or a baseline, with changes that have been made. This gives them the ability to accurately assess the performance impact of that change, which in turn allows them to compensate with more hardware, or further tuning of the applications and OS. The patented methods used by Login VSI provide a quantifiable result for determining the impact of a change in virtual desktop and published application environments.

    Login VSI to test the performance impact of planned patches before and after
    If you wish to test the changes before pushing them into your production environment, then use Login VSI to put a load, representative of your production users, on the system. This will objectively show how much more CPU will be used as a result of the Spectre or Meltdown patches. It is expected that the end users will incur increased latency to their applications and desktops as a result of the higher CPU utilization.

    Login PI to actively monitor the performance impact of unplanned patches and updates
    While not recommended, if you are planning on pushing the patches into your production environment to “see how it goes”, then you can rely on Login PI to get accurate feedback of application performance, before and after the patches have been installed. Latency is expected to increase as a result of higher CPU utilization.

    Login VSI has started a series of lab tests to objectively quantify the exact performance impact of the different security patches rolled out today, and will keep doing so until the problems are contained. The results of these tests will be available on, and shared on our social media. Keep posted for more news…

    Reference materials:

    About the author
    Brian Martynowicz

    Brian is Login VSI’s Director of Customer Services. He is responsible for ensuring operational excellence in supporting and implementing our solutions within customer environments. Having worked in IT consulting for the last 15 years he loves to share field engineering expertise, and customer services management experience with others. In his free time, you will find him blogging or producing vlogs for LinkedIn. His written content is syndicated on Citrixology.