| From | Frederic Weisbecker <> | Subject | [PATCH 17/32] rcu: Restart tick if we enqueue a callback in a nohz/cpuset CPU | Date | Wed, 21 Mar 2012 14:58:23 +0100 |
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If we enqueue an rcu callback, we need the CPU tick to stay alive until we take care of those by completing the appropriate grace period.
Thus, when we call_rcu(), send a self IPI that checks rcu_needs_cpu() so that we restore a periodic tick behaviour that can take care of everything.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Alessio Igor Bogani <abogani@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Avi Kivity <avi@redhat.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Max Krasnyansky <maxk@qualcomm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Hemminger <shemminger@vyatta.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Sven-Thorsten Dietrich <thebigcorporation@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Zen Lin <zen@openhuawei.org> --- kernel/rcutree.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 3fffc26..b8d300c 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1749,6 +1749,13 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), else trace_rcu_callback(rsp->name, head, rdp->qlen); + /* Restart the timer if needed to handle the callbacks */ + if (cpuset_adaptive_nohz()) { + /* Make updates on nxtlist visible to self IPI */ + barrier(); + smp_cpuset_update_nohz(smp_processor_id()); + } + /* If interrupts were disabled, don't dive into RCU core. */ if (irqs_disabled_flags(flags)) { local_irq_restore(flags); -- 1.7.5.4
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