On Sun, Feb 25, 2018 at 11:57:48PM -0500, Steven Rostedt wrote:
> On Sun, 25 Feb 2018 10:17:30 -0800
> "Paul E. McKenney" <paul...@linux.vnet.ibm.com> wrote:
>
>
> > And probably not. You are probably running CONFIG_PREEMPT=y (otherwise
> > RCU-tasks is trivial), so cond_resched() is a complete no-op:
> >
> > static inline int _cond_resched(void) { return 0; }
> >
> > I could make this call rcu_all_qs(), but I would not expect Peter Zijlstra
> > to be at all happy with that sort of change.
> >
> > And the people who asked for the cond_resched() work probably aren't
> > going to be happy with the resumed proliferation of cond_resched_rcu_qs().
> >
> > Hmmm... Grasping at straws... Could we make cond_resched() be something
> > like a tracepoint and instrument them with cond_resched_rcu_qs() if the
> > current RCU-tasks grace period ran for more that (say) a minute of its
> > ten-minute stall-warning span?
> >
>
> Instead of monkeying with cond_resched(), since this is "special" code,
> why don't I just have that code call it directly?
>
> cond_resched();
> rcu_note_voluntary_context_switch(current);
The advantage of the last patch that I sent is that the special call
is in one place. (This is the one that adds the "special" definition
for _cond_resched().)
Thanx, Paul
