On 10/12/2020 11:39 AM, Sean V Kelley wrote:
Are you attempting a tick-less run? I’ve seen the NO_HZ_FULL (full dynticks) feature behave somewhat inconsistently when PREEMPT_RT is enabled. The timer ticks suppression feature can at times appear to be not functioning. I’m curious about how you are attempting to isolate the cores.
We're trying to run tickess on a subset of the CPUs, using a combination of isolcpus, irqaffinity, rcu_nocbs, and nohz_full boot args, as well as runtime affinity adjustment for tasks and IRQs.
I don't think we're seeing full suppression of timer ticks, but partial suppression is happening. Application CPUs are showing as low as 10K interrupts for LOC while the housekeeping CPUs are 300-500 million.
Chris
