On Mon, 2023-09-25 at 18:30 +0200, g.medini@xxxxxxxxxxx wrote: > # tracer: wakeup_rt > # > # wakeup_rt latency trace v1.1.5 on 5.19.0-rt10 > # -------------------------------------------------------------------- > # latency: 357 us, #401/401, CPU#0 | (M:preempt_rt VP:0, KP:0, SP:0 HP:0 #P:2) > # ----------------- > # | task: ktimers/0-15 (uid:0 nice:0 policy:1 rt_prio:1) > # ----------------- The first thing that pokes me in the eye is that priority. I'd bump that a lot. As it sits, anything high priority ktimers may wake when it finally gets the CPU gets to enjoy all the latency ktimers is eating in this trace due to it having been deemed relatively unimportant. Trace starting at 37us vs 0 makes me suspect box wasn't being all it can be at the time. Dunno if that's the case, but I'd suggest taking cpufreq out of the picture when latency source hunting in general. -Mike
