rcu: Remove expedited GP funnel-lock bypass
Commit #cdacbe1f91264 ("rcu: Add fastpath bypassing funnel locking")
turns out to be a pessimization at high load because it forces a tree
full of tasks to wait for an expedited grace period that they probably
do not need. This commit therefore removes this optimization.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt
index ec6998b..00a3a38 100644
--- a/Documentation/RCU/trace.txt
+++ b/Documentation/RCU/trace.txt
@@ -237,17 +237,17 @@
The output of "cat rcu/rcu_preempt/rcuexp" looks as follows:
-s=21872 wd0=0 wd1=0 wd2=0 wd3=5 n=0 enq=0 sc=21872
+s=21872 wd1=0 wd2=0 wd3=5 n=0 enq=0 sc=21872
These fields are as follows:
o "s" is the sequence number, with an odd number indicating that
an expedited grace period is in progress.
-o "wd0", "wd1", "wd2", and "wd3" are the number of times that an
- attempt to start an expedited grace period found that someone
- else had completed an expedited grace period that satisfies the
- attempted request. "Our work is done."
+o "wd1", "wd2", and "wd3" are the number of times that an attempt
+ to start an expedited grace period found that someone else had
+ completed an expedited grace period that satisfies the attempted
+ request. "Our work is done."
o "n" is number of times that a concurrent CPU-hotplug operation
forced a fallback to a normal grace period.