Wakeup latency of all systems - Real-time optimization - Peer-to-peer UDP duplex link - OPC UA PubSub over TSN - Powerlink - Ethercat - Network load - kvm - Sleep states

One of the Linux real-time test systems (rack #3, slot #3) regularly starts a virtualized guest system using the Linux kernel virtual machine (kvm). The guest operating system is Windows XP. Immediately after the guest system is booted up, the vTask Studio testing and automation environment is started that, in turn, repeatedly runs the FreshDiagnose benchmark program in a tight loop which approximately takes 30 minutes to complete. Thereafter, the program ends, and the guest system goes into idle mode for another 15 minutes. The system is then shutdown. The entire procedure is executed once per hour seven times in the morning and seven times in the afternoon.

The recordings below show the real-time capabilities (worst-case combined timer and wakeup latency) of the host system and the load and the uptime of the guest system. The test is undertaken to verify that booting and running a Windows XP guest system under kvm has no impact on the real-time capabilities of the host system. The periods of elevated worst-case latency solely reflect the clock frequency (P states) and the sleep states (C states) of the processor cores that are set to maximum performance only during cyclictest measurements (details are given here).

Screen snapshot of the guest system

At the end of every test run, the guest system creates a snapshot of the screen. It is then saved via Windows network share on the host file system, transferred to the OSADL Webserver and displayed below. Click on the image to show the screen snapshot at full size.