On Tue, 27 Feb 2018 07:36:46 -0800
"Paul E. McKenney" <paul...@linux.vnet.ibm.com> wrote:
> > > --- a/include/linux/sched.h
> > > +++ b/include/linux/sched.h
> > > @@ -1589,6 +1589,12 @@ static inline int test_tsk_need_resched(struct
> > > task_struct *tsk)
> > > */
> > > #ifndef CONFIG_PREEMPT
> > > extern int _cond_resched(void);
> > > +#elif defined(CONFIG_TASKS_RCU)
> > > +static inline int _cond_resched(void)
> > > +{
> > > + rcu_note_voluntary_context_switch(current);
> > > + return 0;
> > > +}
> > > #else
> > > static inline int _cond_resched(void) { return 0; }
> > > #endif
> >
> >
> > This does work, but so does the below, without causing cond_resched()
> > from being something other than a nop of CONFIG_PREEMPT.
>
> True, but based on the cond_resched_rcu_qs() experience, I bet that
> trace_benchmark.c won't be the only place needing help.
Perhaps, still think this is a special case. That said, perhaps
cond_resched isn't done in critical locations as it's a place that is
explicitly stating that it's OK to schedule.
-- Steve
