From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Sat, 22 Jun 2013 18:59:35 +0000 (-0400)
Subject: doc/examples: add synchronize_rcu()
X-Git-Tag: v0.8.0~20
X-Git-Url: https://git.lttng.org/?p=urcu.git;a=commitdiff_plain;h=d7818a6fd0c57b576f3bacc67ddd62bc8a78fb05

doc/examples: add synchronize_rcu()

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/doc/examples/urcu-flavors/mb.c b/doc/examples/urcu-flavors/mb.c
index 757fe9e..62ad54b 100644
--- a/doc/examples/urcu-flavors/mb.c
+++ b/doc/examples/urcu-flavors/mb.c
@@ -117,6 +117,15 @@ int main(int argc, char **argv)
 		call_rcu(&node->rcu_head, rcu_free_node);
 	}
 
+	/*
+	 * We can also wait for a quiescent state by calling
+	 * synchronize_rcu() rather than using call_rcu(). It is usually
+	 * a slower approach than call_rcu(), because the latter can
+	 * batch work. Moreover, call_rcu() can be called from a RCU
+	 * read-side critical section, but synchronize_rcu() should not.
+	 */
+	synchronize_rcu();
+
 	sleep(1);
 
 	/*
diff --git a/doc/examples/urcu-flavors/membarrier.c b/doc/examples/urcu-flavors/membarrier.c
index 0c5be4c..21f4579 100644
--- a/doc/examples/urcu-flavors/membarrier.c
+++ b/doc/examples/urcu-flavors/membarrier.c
@@ -116,6 +116,15 @@ int main(int argc, char **argv)
 		call_rcu(&node->rcu_head, rcu_free_node);
 	}
 
+	/*
+	 * We can also wait for a quiescent state by calling
+	 * synchronize_rcu() rather than using call_rcu(). It is usually
+	 * a slower approach than call_rcu(), because the latter can
+	 * batch work. Moreover, call_rcu() can be called from a RCU
+	 * read-side critical section, but synchronize_rcu() should not.
+	 */
+	synchronize_rcu();
+
 	sleep(1);
 
 	/*
diff --git a/doc/examples/urcu-flavors/qsbr.c b/doc/examples/urcu-flavors/qsbr.c
index 6f5b9b5..1dbd546 100644
--- a/doc/examples/urcu-flavors/qsbr.c
+++ b/doc/examples/urcu-flavors/qsbr.c
@@ -126,6 +126,16 @@ int main(int argc, char **argv)
 
 	rcu_thread_online();
 
+	/*
+	 * We can also wait for a quiescent state by calling
+	 * synchronize_rcu() rather than using call_rcu(). It is usually
+	 * a slower approach than call_rcu(), because the latter can
+	 * batch work. Moreover, call_rcu() can be called from a RCU
+	 * read-side critical section, but synchronize_rcu() ensures the
+	 * caller thread is offline, thus acting as a quiescent state.
+	 */
+	synchronize_rcu();
+
 	/*
 	 * Waiting for previously called call_rcu handlers to complete
 	 * before program exits, or in library destructors, is a good
diff --git a/doc/examples/urcu-flavors/signal.c b/doc/examples/urcu-flavors/signal.c
index b7c279c..136c380 100644
--- a/doc/examples/urcu-flavors/signal.c
+++ b/doc/examples/urcu-flavors/signal.c
@@ -116,6 +116,15 @@ int main(int argc, char **argv)
 		call_rcu(&node->rcu_head, rcu_free_node);
 	}
 
+	/*
+	 * We can also wait for a quiescent state by calling
+	 * synchronize_rcu() rather than using call_rcu(). It is usually
+	 * a slower approach than call_rcu(), because the latter can
+	 * batch work. Moreover, call_rcu() can be called from a RCU
+	 * read-side critical section, but synchronize_rcu() should not.
+	 */
+	synchronize_rcu();
+
 	sleep(1);
 
 	/*