X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=README;h=93c0a742cedda21928f5333f93737409819f0908;hb=7ac06cef7a7d9394332837edc5c0e9595286a5fc;hp=02cec268ac359d988d1ce3c811b2980e98ae385d;hpb=0d21ab2de8ec0b6607654e0122a1302639d6fe5b;p=urcu.git

diff --git a/README b/README
index 02cec26..93c0a74 100644
--- a/README
+++ b/README
@@ -1,14 +1,82 @@
-build instructions for userspace-rcu library :
+Userspace RCU Implementation
+by Mathieu Desnoyers and Paul E. McKenney
 
-make
-make install
+BUILDING
+--------
 
-Usage :
+	make
+	make install
+	
 
-Registration of _each thread_ calling read-side critical sections must be done
-with rcu_register_thread() before using rcu_read_lock()/rcu_read_unlock().
+QUICK START GUIDE
+-----------------
+
+Initialization
+
+	Each thread that has reader critical sections (that uses
+	rcu_read_lock()/rcu_read_unlock() must first register to the URCU
+	library. This is done by calling rcu_register_thread().
+
+Reading
+
+	Reader critical sections must be protected by locating them between
+	calls to rcu_read_lock() and rcu_read_unlock(). Inside that lock,
+	rcu_dereference() may be called to read an RCU protected pointer.
+
+Writing
+
+	rcu_assign_pointer() and rcu_xchg_pointer() may be called anywhere.
+	After, synchronize_rcu() must be called. When it returns, the old
+	values are not in usage anymore.
+
+Being careful with signals
+
+	The urcu library uses signals internally. The signal handler is
+	registered with the SA_RESTART flag. However, these signals may cause
+	some non-restartable system calls to fail with errno = EINTR. Care
+	should be taken to restart system calls manually if they fail with this
+	error. A list of non-restartable system calls may be found in
+	signal(7). To ensure the Userspace RCU library does not use signals,
+	see "Usage of liburcu-mb" below.
+
+	Read-side critical sections can are allowed in a signal handler with
+	liburcu and liburcu-mb. Be careful, however, to disable these signals
+	between thread creation and calls to rcu_register_thread(), because a
+	signal handler nesting on an unregistered thread would not be allowed to
+	call rcu_read_lock().
+
+Usage of liburcu
+
+	This is the preferred version of the library, both in terms of speed and
+	flexibility. Define _LGPL_SOURCE if your code is LGPL or GPL (otherwise
+	function calls will be generated instead of inlines). Use the urcu.h
+	header.  Link the application with "-lurcu".
+
+Usage of liburcu-mb
+
+	Compile code with "-DCONFIG_URCU_AVOID_SIGNALS" and link with
+	"-lurcu-mb" to use a version of the urcu library which does not need to
+	reserve a signal number. CONFIG_URCU_AVOID_SIGNALS uses full SMP
+	barriers for readers. This eliminates the need for signals but results
+	in slower reads.
+
+Usage of liburcu-qsbr
+
+	The QSBR flavor of RCU needs to have each reader thread executing
+	rcu_quiescent_state() periodically to progress. rcu_thread_online() and
+	rcu_thread_offline() can be used to mark long periods for which the
+	threads are not active. Link with "-lurcu-qsbr" and use urcu-qsbr.h.
+
+Usage of DEBUG_RCU
+
+	DEBUG_RCU is used to add internal debugging self-checks to the
+	RCU library. This define adds a performance penality when enabled.
+	Can be enabled by uncommenting the corresponding line in
+	Makefile.build.inc.
+
+Usage of DEBUG_YIELD
+
+	DEBUG_YIELD is used to add random delays in the code for testing
+	purposes.
 
-Unregistration should be performed with rcu_unregister_thread() before exiting
-the thread.
 
-     Mathieu Desnoyers