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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2009-08-22 16:56:53 -0400
committerIngo Molnar <mingo@elte.hu>2009-08-23 04:32:40 -0400
commit6b3ef48adf847f7adf11c870e3ffacac150f1564 (patch)
treee1403ce515bf00ade99ec806f6ab6b6db999aa0b /Documentation/RCU
parentf41d911f8c49a5d65c86504c19e8204bb605c4fd (diff)
rcu: Remove CONFIG_PREEMPT_RCU
Now that CONFIG_TREE_PREEMPT_RCU is in place, there is no further need for CONFIG_PREEMPT_RCU. Remove it, along with whatever subtle bugs it may (or may not) contain. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: josht@linux.vnet.ibm.com Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org LKML-Reference: <125097461396-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'Documentation/RCU')
-rw-r--r--Documentation/RCU/rcu.txt10
-rw-r--r--Documentation/RCU/whatisRCU.txt8
2 files changed, 9 insertions, 9 deletions
diff --git a/Documentation/RCU/rcu.txt b/Documentation/RCU/rcu.txt
index 7aa2002ade77..2a23523ce471 100644
--- a/Documentation/RCU/rcu.txt
+++ b/Documentation/RCU/rcu.txt
@@ -36,7 +36,7 @@ o How can the updater tell when a grace period has completed
36 executed in user mode, or executed in the idle loop, we can 36 executed in user mode, or executed in the idle loop, we can
37 safely free up that item. 37 safely free up that item.
38 38
39 Preemptible variants of RCU (CONFIG_PREEMPT_RCU) get the 39 Preemptible variants of RCU (CONFIG_TREE_PREEMPT_RCU) get the
40 same effect, but require that the readers manipulate CPU-local 40 same effect, but require that the readers manipulate CPU-local
41 counters. These counters allow limited types of blocking 41 counters. These counters allow limited types of blocking
42 within RCU read-side critical sections. SRCU also uses 42 within RCU read-side critical sections. SRCU also uses
@@ -79,10 +79,10 @@ o I hear that RCU is patented? What is with that?
79o I hear that RCU needs work in order to support realtime kernels? 79o I hear that RCU needs work in order to support realtime kernels?
80 80
81 This work is largely completed. Realtime-friendly RCU can be 81 This work is largely completed. Realtime-friendly RCU can be
82 enabled via the CONFIG_PREEMPT_RCU kernel configuration parameter. 82 enabled via the CONFIG_TREE_PREEMPT_RCU kernel configuration
83 However, work is in progress for enabling priority boosting of 83 parameter. However, work is in progress for enabling priority
84 preempted RCU read-side critical sections. This is needed if you 84 boosting of preempted RCU read-side critical sections. This is
85 have CPU-bound realtime threads. 85 needed if you have CPU-bound realtime threads.
86 86
87o Where can I find more information on RCU? 87o Where can I find more information on RCU?
88 88
diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt
index 97ded2432c59..e41a7fecf0d3 100644
--- a/Documentation/RCU/whatisRCU.txt
+++ b/Documentation/RCU/whatisRCU.txt
@@ -136,10 +136,10 @@ rcu_read_lock()
136 Used by a reader to inform the reclaimer that the reader is 136 Used by a reader to inform the reclaimer that the reader is
137 entering an RCU read-side critical section. It is illegal 137 entering an RCU read-side critical section. It is illegal
138 to block while in an RCU read-side critical section, though 138 to block while in an RCU read-side critical section, though
139 kernels built with CONFIG_PREEMPT_RCU can preempt RCU read-side 139 kernels built with CONFIG_TREE_PREEMPT_RCU can preempt RCU
140 critical sections. Any RCU-protected data structure accessed 140 read-side critical sections. Any RCU-protected data structure
141 during an RCU read-side critical section is guaranteed to remain 141 accessed during an RCU read-side critical section is guaranteed to
142 unreclaimed for the full duration of that critical section. 142 remain unreclaimed for the full duration of that critical section.
143 Reference counts may be used in conjunction with RCU to maintain 143 Reference counts may be used in conjunction with RCU to maintain
144 longer-term references to data structures. 144 longer-term references to data structures.
145 145