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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2016-01-31 04:23:19 +0300
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2016-03-31 23:34:07 +0300
commite2fd9d35847d1936398d44c4df68dceb3d7f64e7 (patch)
tree1893e200e6f5e87065b38fedfc9f74d19a4079b7 /Documentation/RCU
parent4f41530245c7fd4837152e264d120d05ae940eb0 (diff)
downloadlinux-e2fd9d35847d1936398d44c4df68dceb3d7f64e7.tar.xz
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>
Diffstat (limited to 'Documentation/RCU')
-rw-r--r--Documentation/RCU/trace.txt10
1 files changed, 5 insertions, 5 deletions
diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt
index ec6998b1b6d0..00a3a38b375a 100644
--- a/Documentation/RCU/trace.txt
+++ b/Documentation/RCU/trace.txt
@@ -237,17 +237,17 @@ o "ktl" is the low-order 16 bits (in hexadecimal) of the count of
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.