A common question that SystemTap can be used to answer involves how often particular events occur on the system. Some events, such as system calls, can happen frequently and the goal is to make the SystemTap script as efficient as possible.
Using the statistical aggregate in the place of regular integers is one way to improve the performance of SystemTap scripts. The statistical aggregates record data on a per-CPU basis to reduce the amount of coordination required between processors, allowing information to be recorded with less overhead. In this article, I’ll show an example of how to reduce overhead in SystemTap scripts.
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For those unfamiliar, Open Virtual Network (OVN) is a subproject of OpenVswitch (OVS), a performant programmable multi-platform virtual switch. OVN provides the ability to express an overlay network as a series of virtual routers and switches. OVN also provides native methods for setting up Access Control Lists (ACLs), and it functions as an OpenFlow switch, providing services such as DHCP. The components of OVN program OVS on each of the hypervisors in the network. Many of Red Hat’s products, such as Red Hat OpenStack Platform and Red Hat Virtualization, are now using OVN. Red Hat OpenShift Container Platform will be using OVN soon.
Looking around the internet, it’s pretty easy to find high-quality tutorials on the basics of OVN. However, when it comes to more-advanced topics, it sometimes feels like the amount of information is lacking. In this tutorial, we’ll examine dynamic addressing in OVN. You will learn about IP address management (IPAM) options in OVN and how to apply them.
Continue reading “Dynamic IP Address Management in Open Virtual Network (OVN): Part One”
In my previous post, Introduction to Eclipse Vert.x, we developed a very simple Vert.x application and saw how this application can be tested, packaged, and executed. That was nice, wasn’t it? Well, that was only the beginning. In this post, we are going to enhance our application to support external configuration, and learn how to deal with different configuration sources.
Continue reading “Eclipse Vert.x Application Configuration (Part 2 of Introduction to Vert.x)”
In this blog post, I will demonstrate how to perform SPKI (Subject Public Key Info) Pinning in an Android Application using TrustKit – a pinning library for Android.
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