On 2022-03-23, Gautam Thaker <ghthaker@xxxxxxxxx> wrote: > I built 5.15.28-rt35 #2 SMP PREEMPT_RT with “Fully Preemptible > Kernel" option and otherwise using .config from a stock Ubuntu 20.04 > 5.4.0 kernel. > > Quick question: I see scheduling/wake_up latencies around 800 usec and > this is confirmed by cyclictest. [...] > node-0> grep -i preempt /boot/config-5.15.28-rt35 > node-0> grep -i debug /boot/config-5.15.28-rt35 |grep =y [...] > processor : 31 > vendor_id : GenuineIntel > cpu family : 6 > model : 63 > model name : Intel(R) Xeon(R) CPU E5-2630 v3 @ 2.40GHz > stepping : 2 > microcode : 0x46 > cpu MHz : 1200.000 > cache size : 20480 KB Your CPU is running at 1.2GHz although it is capable of 2.4GHz. This looks like you have CPU frequency scaling activated. Investigate: grep -i cpu_freq /boot/config-5.15.28-rt35 The configuration of your tick may also be interesting: grep -i hz /boot/config-5.15.28-rt35 John Ogness
