On Thu, 2012-09-06 at 11:07 -0400, Steven Rostedt wrote: > On Thu, 2012-09-06 at 16:56 +0200, Peter Zijlstra wrote: > > On Thu, 2012-08-30 at 11:56 -0700, Paul E. McKenney wrote: > > > > > > If a given CPU avoids the idle loop but also avoids starting a new > > > RCU grace period for a full minute, RCU can issue spurious RCU CPU > > > stall warnings. This commit fixes this issue by adding a check for > > > ongoing grace period to avoid these spurious stall warnings. > > > > How would it avoid starting a new period for over a minute? fqs should > > happen, right? And holding rcu_read_lock() for over a minute surely is a > > bug. > > I can see this happening in test cases, but it would seem weird on a > normal system. That is, for preempt rcu, having a process scheduled out > holding an rcu_read_lock() for over a minute could happen on a really > stressed out system. But for such a case, I don't think a warning is out > of question.
One would hope that fqs would boost things.. but yeah, if your app is spinning above the rcu boost prio you're still toast. But in that case you're right, a warning is fully deserved. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
