diff options
| author | Paul E. McKenney <paulmck@us.ibm.com> | 2006-06-25 05:48:44 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-06-25 10:01:17 -0700 |
| commit | 165d6c78ee24127dde5c750b2af0a239f9c11d1a (patch) | |
| tree | a9329b5b24893588114441f43d576dfa310e5f43 /Documentation/RCU/whatisRCU.txt | |
| parent | 76d42bd96984832c4ea8bc8cbd74e496ac31409e (diff) | |
[PATCH] RCU documentation: self-limiting updates and call_rcu()
An update to the RCU documentation calling out the
self-limiting-update-rate advantages of synchronize_rcu(), and describing
how to use call_rcu() in a way that results in self-limiting updates.
Self-limiting updates are important to avoiding RCU-induced OOM in face of
denial-of-service attacks.
Signed-off-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'Documentation/RCU/whatisRCU.txt')
| -rw-r--r-- | Documentation/RCU/whatisRCU.txt | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt index 6e459420ee9f..4f41a60e5111 100644 --- a/Documentation/RCU/whatisRCU.txt +++ b/Documentation/RCU/whatisRCU.txt @@ -184,7 +184,17 @@ synchronize_rcu() blocking, it registers a function and argument which are invoked after all ongoing RCU read-side critical sections have completed. This callback variant is particularly useful in situations where - it is illegal to block. + it is illegal to block or where update-side performance is + critically important. + + However, the call_rcu() API should not be used lightly, as use + of the synchronize_rcu() API generally results in simpler code. + In addition, the synchronize_rcu() API has the nice property + of automatically limiting update rate should grace periods + be delayed. This property results in system resilience in face + of denial-of-service attacks. Code using call_rcu() should limit + update rate in order to gain this same sort of resilience. See + checklist.txt for some approaches to limiting the update rate. rcu_assign_pointer() |