X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=README;h=0ec723dea10186d13e6c11705e18a0c8149ae288;hb=cee02f0ab0a6766662490f2d815d487c098c17b1;hp=d71bbe7597e1fb893cd13742cbb16f6e7ef61e1c;hpb=c97ae6eb5bf6baea503d9df98e8376c0bd36b629;p=urcu.git

diff --git a/README b/README
index d71bbe7..0ec723d 100644
--- a/README
+++ b/README
@@ -26,18 +26,35 @@ Reading
 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.
+	After, synchronize_rcu() must be called. When it returns, the old
+	values are not in usage anymore.
 
+Being careful with signals
 
-Usage of DEBUG_FULL_MB
+	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.
 
-	DEBUG_FULL_MB uses full SMP barriers for readers. This eliminates the
-	need for signals but results in slower reads.
+	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.
 
 Usage of DEBUG_YIELD
 
 	DEBUG_YIELD is used to add random delays in the code for testing
 	purposes.
-