On August 20, 2016 3:04:43 PM EDT, Tracy Smith
>Using ftace it is difficult to catch the latency since it can occur at >any >point during the cyclictest. It is an uncomfortable level of >indeterminism >without knowing the cause. > >Is there a way to trace random latency jumps on a single core using >trace, >or any other suggestion to isolate it? I know the functions and tasks >running on the core using ftrace, but can't catch the random latency >jumps. Have you tried using the -b option of cyclictest? It stops the tracing when it detects a latency. It shows what happened up to that point. I can discuss more about what to do later but I'll be traveling to LinuxCon tomorrow. -- Steve > >Thx, Tracy >On Aug 20, 2016 12:54 PM, "Nikolay Borisov" <n.borisov.l...@gmail.com> >wrote: > >> >> >> On 20.08.2016 20:03, T. Smith wrote: >> > The goal is to isolate causes of indeterminism when using the >PREEMPT_RT >> kernel configuration with full preemption and to characterize latency >and >> jitter using ftrace, any recommendations? >> >> What hardware is it ? If it's x86 it's entirely possible you are >seeing >> SMI. Perhaps you should look into disabling those if you are on x86? >> -- Sent from my Android device with K-9 Mail. Please excuse my brevity.
