Documentation/RCU/rcu.rst

3 RCU Concepts
6 The basic idea behind RCU (read-copy update) is to split destructive
11 since dropped their references.  For example, an RCU-protected deletion
14 :ref:`Documentation/RCU/listRCU.rst <list_rcu_doc>` for more information on
15 using RCU with linked lists.
20 - Why would anyone want to use RCU?
22   The advantage of RCU's two-part approach is that RCU readers need
26   on modern CPUs is what gives RCU its performance advantages
27   in read-mostly situations.  The fact that RCU readers need not
31   if the RCU readers give no indication when they are done?
33   Just as with spinlocks, RCU readers are not permitted to
36   three states, we know that that CPU has exited any previous RCU
42   Preemptible variants of RCU (CONFIG_PREEMPT_RCU) get the
45   RCU read-side critical sections.  SRCU also uses CPU-local
46   counters, and permits general blocking within RCU read-side
47   critical sections.  These variants of RCU detect grace periods
53   See :ref:`Documentation/RCU/UP.rst <up_doc>` for more information.
55 - How can I see where RCU is currently used in the Linux kernel?
60   "synchronize_srcu", and the other RCU primitives.  Or grab one
63   (http://www.rdrop.com/users/paulmck/RCU/linuxusage/rculocktab.html).
65 - What guidelines should I follow when writing code that uses RCU?
69 - Why the name "RCU"?
71   "RCU" stands for "read-copy update".
72   :ref:`Documentation/RCU/listRCU.rst <list_rcu_doc>` has more information on where
75 - I hear that RCU is patented?  What is with that?
77   Yes, it is.  There are several known patents related to RCU,
78   search for the string "Patent" in Documentation/RCU/RTFP.txt to find them.
81   There are now also LGPL implementations of user-level RCU
84 - I hear that RCU needs work in order to support realtime kernels?
86   Realtime-friendly RCU can be enabled via the CONFIG_PREEMPT_RCU
89 - Where can I find more information on RCU?
91   See the Documentation/RCU/RTFP.txt file.
92   Or point your browser at (http://www.rdrop.com/users/paulmck/RCU/).