X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=README;h=f9af1eb483d83d3cee27625efc0eaa5c48dbbe3e;hb=fb6e510b9ae45b9b984b4646b4be6b9d7a2bbf7c;hp=c571af521d69307be1ac701e3c5366953b30553d;hpb=aa8c36e03126a731c6c925cb32a8649c9802198d;p=urcu.git

diff --git a/README b/README
index c571af5..f9af1eb 100644
--- a/README
+++ b/README
@@ -1,18 +1,62 @@
-build instructions for userspace-rcu library :
+Userspace RCU Implementatation
+by Mathieu Desnoyers and Paul E. McKenney
 
-make pthreads-x86
-or
-make pthreads-ppc
+BUILDING
+--------
 
-make
-make install
+	make
+	make install
+	
 
-Usage :
+QUICK START GUIDE
+-----------------
 
-Registration of _each thread_ calling read-side critical sections must be done
-with rcu_register_thread() before using rcu_read_lock()/rcu_read_unlock().
+Initialization
 
-Unregistration should be performed with rcu_unregister_thread() before exiting
-the thread.
+	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().
 
-     Mathieu Desnoyers
+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 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,
+	define CONFIG_URCU_AVOID_SIGNALS at compile-time.
+
+	Read-side critical sections can sit in a signal handler. 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 CONFIG_URCU_AVOID_SIGNALS
+
+	CONFIG_URCU_AVOID_SIGNALS uses full SMP barriers for readers. This
+	eliminates the need for signals but results in slower reads.
+
+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.