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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2016-01-30 20:23:19 -0500
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2016-03-31 16:34:07 -0400
commite2fd9d35847d1936398d44c4df68dceb3d7f64e7 (patch)
tree1893e200e6f5e87065b38fedfc9f74d19a4079b7 /Documentation/RCU
parent4f41530245c7fd4837152e264d120d05ae940eb0 (diff)
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
237 237
238The output of "cat rcu/rcu_preempt/rcuexp" looks as follows: 238The output of "cat rcu/rcu_preempt/rcuexp" looks as follows:
239 239
240s=21872 wd0=0 wd1=0 wd2=0 wd3=5 n=0 enq=0 sc=21872 240s=21872 wd1=0 wd2=0 wd3=5 n=0 enq=0 sc=21872
241 241
242These fields are as follows: 242These fields are as follows:
243 243
244o "s" is the sequence number, with an odd number indicating that 244o "s" is the sequence number, with an odd number indicating that
245 an expedited grace period is in progress. 245 an expedited grace period is in progress.
246 246
247o "wd0", "wd1", "wd2", and "wd3" are the number of times that an 247o "wd1", "wd2", and "wd3" are the number of times that an attempt
248 attempt to start an expedited grace period found that someone 248 to start an expedited grace period found that someone else had
249 else had completed an expedited grace period that satisfies the 249 completed an expedited grace period that satisfies the attempted
250 attempted request. "Our work is done." 250 request. "Our work is done."
251 251
252o "n" is number of times that a concurrent CPU-hotplug operation 252o "n" is number of times that a concurrent CPU-hotplug operation
253 forced a fallback to a normal grace period. 253 forced a fallback to a normal grace period.