On Mon, Apr 1, 2024 at 8:20 AM Honglei Wang <jameshongleiwang@xxxxxxx> wrote: > On 2024/3/28 14:27, mingyang.cui wrote: > > When rt_mutex_setprio changes a task's scheduling class to RT, > > sometimes the task's vruntime is not updated correctly upon > > return to the fair class. > > Specifically, the following is being observed: > > - task has just been created and running for a short time > > - task sleep while still in the fair class > > - task is boosted to RT via rt_mutex_setprio, which changes > > the task to RT and calls check_class_changed. > > - check_class_changed leads to detach_task_cfs_rq, at which point > > the vruntime_normalized check sees that the task's sum_exec_runtime > > is zero, which results in skipping the subtraction of the > > rq's min_vruntime from the task's vruntime > > Did you do the test on the latest tree? vruntime_normalized was removed > by e8f331bcc2 (sched/smp: Use lag to simplify cross-runqueue placement). Indeed (I was looking at an older tree last week and missed it was removed as well). Though something like this change probably will be needed for the -stable trees? thanks -john
