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> > > u32 kf_mask; /* see scx_kf_mask above */ > > > struct task_struct *kf_tasks[2]; /* see SCX_CALL_OP_TASK() */ > > > + struct rq *locked_rq; /* currently locked rq */ > > > > Can this be a percpu variable? While rq is locked, current can't switch out > > anyway and that way we don't have to increase the size of task. Note that > > kf_tasks[] are different in that some ops may, at least theoretically, > > sleep. > > Yeah, I was debating between using a percpu variable or storing it in > current. I went with current just to stay consistent with kf_tasks. > > But you're right about not to increasing the size of the task, and as you > pointed out, we can’t switch if the rq is locked, so a percpu variable > should work. I’ll update that in v2. Hm... actually thinking more about this, a problem with the percpu variable is that, if no rq is locked, we could move to a different CPU and end up reading the wrong rq_locked via scx_locked_rq(). I don't think we want to preempt_disable/enable all the callbacks just to fix this... Maybe storing in current is a safer choice? Thanks, -Andrea