2013/4/13 Paul E. McKenney <paul...@linux.vnet.ibm.com>: > From: "Paul E. McKenney" <paul...@linux.vnet.ibm.com> > > Adaptive-ticks CPUs inform RCU when they enter kernel mode, but they do > not necessarily turn the scheduler-clock tick back on. This state of > affairs could result in RCU waiting on an adaptive-ticks CPU running > for an extended period in kernel mode. Such a CPU will never run the > RCU state machine, and could therefore indefinitely extend the RCU state > machine, sooner or later resulting in an OOM condition. > > This patch, inspired by an earlier patch by Frederic Weisbecker, therefore > causes RCU's force-quiescent-state processing to check for this condition > and to send an IPI to CPUs that remain in that state for too long. > "Too long" currently means about three jiffies by default, which is > quite some time for a CPU to remain in the kernel without blocking. > The rcu_tree.jiffies_till_first_fqs and rcutree.jiffies_till_next_fqs > sysfs variables may be used to tune "too long" if needed. > > Reported-by: Frederic Weisbecker <fweis...@gmail.com> > Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
It might be better if I take this patch to get it through tip:timers/nohz so that I can keep it in sync with the rest. What do you think? Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
