diff options
author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2016-01-30 20:23:19 -0500 |
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committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2016-03-31 16:34:07 -0400 |
commit | e2fd9d35847d1936398d44c4df68dceb3d7f64e7 (patch) | |
tree | 1893e200e6f5e87065b38fedfc9f74d19a4079b7 /Documentation/RCU | |
parent | 4f41530245c7fd4837152e264d120d05ae940eb0 (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.txt | 10 |
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 | ||
238 | The output of "cat rcu/rcu_preempt/rcuexp" looks as follows: | 238 | The output of "cat rcu/rcu_preempt/rcuexp" looks as follows: |
239 | 239 | ||
240 | s=21872 wd0=0 wd1=0 wd2=0 wd3=5 n=0 enq=0 sc=21872 | 240 | s=21872 wd1=0 wd2=0 wd3=5 n=0 enq=0 sc=21872 |
241 | 241 | ||
242 | These fields are as follows: | 242 | These fields are as follows: |
243 | 243 | ||
244 | o "s" is the sequence number, with an odd number indicating that | 244 | o "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 | ||
247 | o "wd0", "wd1", "wd2", and "wd3" are the number of times that an | 247 | o "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 | ||
252 | o "n" is number of times that a concurrent CPU-hotplug operation | 252 | o "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. |