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authorPaul E. McKenney <paul.mckenney@linaro.org>2012-05-05 19:10:35 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-06-06 20:43:27 -0700
commitfd4b352687fd8604d49c190c4c9ea9e369fd42d5 (patch)
tree1e20de9090f7d74eef642ac263dd71da0b494d7d
parent8f5af6f1f2d09fe5eac86a5dc1731a5917c1503a (diff)
rcu: Update RCU_FAST_NO_HZ tracing for lazy callbacks
In the current code, a short dyntick-idle interval (where there is at least one non-lazy callback on the CPU) and a long dyntick-idle interval (where there are only lazy callbacks on the CPU) are traced identically, which can be less than helpful. This commit therefore emits different event traces in these two cases. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com> Tested-by: Pascal Chapperon <pascal.chapperon@wanadoo.fr>
-rw-r--r--include/trace/events/rcu.h1
-rw-r--r--kernel/rcutree_plugin.h8
2 files changed, 6 insertions, 3 deletions
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index 1480900c511..d274734b2aa 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -289,6 +289,7 @@ TRACE_EVENT(rcu_dyntick,
* "In holdoff": Nothing to do, holding off after unsuccessful attempt.
* "Begin holdoff": Attempt failed, don't retry until next jiffy.
* "Dyntick with callbacks": Entering dyntick-idle despite callbacks.
+ * "Dyntick with lazy callbacks": Entering dyntick-idle w/lazy callbacks.
* "More callbacks": Still more callbacks, try again to clear them out.
* "Callbacks drained": All callbacks processed, off to dyntick idle!
* "Timer": Timer fired to cause CPU to continue processing callbacks.
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 2411000d986..5449f02c482 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -2165,15 +2165,17 @@ static void rcu_prepare_for_idle(int cpu)
!rcu_pending(cpu) &&
!local_softirq_pending()) {
/* Can we go dyntick-idle despite still having callbacks? */
- trace_rcu_prep_idle("Dyntick with callbacks");
per_cpu(rcu_dyntick_drain, cpu) = 0;
per_cpu(rcu_dyntick_holdoff, cpu) = jiffies;
- if (rcu_cpu_has_nonlazy_callbacks(cpu))
+ if (rcu_cpu_has_nonlazy_callbacks(cpu)) {
+ trace_rcu_prep_idle("Dyntick with callbacks");
per_cpu(rcu_idle_gp_timer_expires, cpu) =
jiffies + RCU_IDLE_GP_DELAY;
- else
+ } else {
per_cpu(rcu_idle_gp_timer_expires, cpu) =
jiffies + RCU_IDLE_LAZY_GP_DELAY;
+ trace_rcu_prep_idle("Dyntick with lazy callbacks");
+ }
tp = &per_cpu(rcu_idle_gp_timer, cpu);
mod_timer_pinned(tp, per_cpu(rcu_idle_gp_timer_expires, cpu));
per_cpu(rcu_nonlazy_posted_snap, cpu) =