On 2023-05-30 12:51:48 [+0200], Kegl Rohit wrote: > Hello! Hi, > But for my understanding RCU_BOOST should help here, even if the rt > app is not implemented correctly? RCU_BOOST will help to move a task outside of its rcu_read() section if it got preempted there. Otherwise the RCU machine can't make progress and free after a grace period. If a task with low priority is stuck in such a section, then RCU_BOOST will help to move it out. This requires that the high-priority task gets into a RCU section for it work (usually not a problem but wouldn't happen if a task loops 100% in userland). >From you describe, your RCU warning came probably from the fact that your application is consuming 100% of the CPU. Your RT task needs to rest from to time so that other kernel threads get their turn. By enabling callback offloading and moving that RCU thread another CPU you ensure that the completion callbacks get invoked. Then you need to ensure that RCU can assure that it makes progress. This is probably what triggers here. There is another thread for that but this one can only be offloaded with CONFIG_NOHZ_FULL. > Thanks in advance! Sebastian
