On Tue, Aug 22, 2023 at 3:37 AM Z qiang <qiang.zhang1211@xxxxxxxxx> wrote: > > When running build-in rcutorture tests in 6.5.0-rc4-rt, and found that, > although the value of /proc/sys/kernel/sched_rt_runtime_us is -1, > > cat /sys/kernel/debug/sched/debug > .... > rt_rq[6]: > .rt_nr_running : 4 > .rt_nr_migratory : 0 > .rt_throttled : 0 > .rt_time : 0.000000 > .rt_runtime : 950.000000 > > but the rt_runtime still is 950.000000. > set sysctl_sched_rt_runtime in rcu_torture_disable_rt_throttle() > does not disable rt-throttling. I think you have hit a bug. I think the problem is rcu_torture_disable_rt_throttle() modifies the sysctl knobs, but does not change def_rt_bandwidth and reinitialize the rt_rq. I think we need to call sched_rt_do_global() like the sysfs handler does, or change the sysctl knobs to be earlier in the boot process before the rt_rq are initialized. Or better yet (not sure if it is possible) trigger the sysctl change via the sysctl layer and let it do the same logic. Thoughts? Thanks.
