Hi Paul, On Mon, May 13, 2013 at 07:00:05AM -0700, Paul E. McKenney wrote: > rcu: Fix comparison sense in rcu_needs_cpu() > > Commit c0f4dfd4f (rcu: Make RCU_FAST_NO_HZ take advantage of numbered > callbacks) introduced a bug that can result in excessively long grace > periods. This bug reverse the senes of the "if" statement checking > for lazy callbacks, so that RCU takes a lazy approach when there are > in fact non-lazy callbacks. This can result in excessive boot, suspend, > and resume times. > > This commit therefore fixes the sense of this "if" statement. > > Reported-by: Borislav Petkov <[email protected]> > Reported-by: Bjørn Mork <[email protected]> > Reported-by: Joerg Roedel <[email protected]> > Signed-off-by: Paul E. McKenney <[email protected]>
Just tested the patch, it fixes the long boot delay for me. Thanks for fixing this. Tested-by: Joerg Roedel <[email protected]> > > diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h > index 641991d..63098a5 100644 > --- a/kernel/rcutree_plugin.h > +++ b/kernel/rcutree_plugin.h > @@ -1692,7 +1692,7 @@ int rcu_needs_cpu(int cpu, unsigned long *dj) > rdtp->last_accelerate = jiffies; > > /* Request timer delay depending on laziness, and round. */ > - if (rdtp->all_lazy) { > + if (!rdtp->all_lazy) { > *dj = round_up(rcu_idle_gp_delay + jiffies, > rcu_idle_gp_delay) - jiffies; > } else { > -- 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/
