On Wed, 2020-09-02 at 17:15 +0530, Pratik Rajesh Sampat wrote: > Measure cpuidle latencies on wakeup to determine and compare with the > advertsied wakeup latencies for each idle state. It looks like the measurements include more than just C-state wake, they also include the overhead of waking up the proces, context switch, and potentially any interrupts that happen on that CPU. I am not saying this is not interesting data, it surely is, but it is going to be larger than you see in cpuidle latency tables. Potentially significantly larger. Therefore, I am not sure this program should be advertised as "cpuidle measurement". It really measures the "IPI latency" in case of the IPI method. > A baseline measurement for each case of IPI and timers is taken at > 100 percent CPU usage to quantify for the kernel-userpsace overhead > during execution. At least on Intel platforms, this will mean that the IPI method won't cover deep C-states like, say, PC6, because one CPU is busy. Again, not saying this is not interesting, just pointing out the limitation. I was working on a somewhat similar stuff for x86 platforms, and I am almost ready to publish that on github. I can notify you when I do so if you are interested. But here is a small presentation of the approach that I did on Plumbers last year: https://youtu.be/Opk92aQyvt0?t=8266 (the link points to the start of my talk)
