From 0825458b1dbc39ec6840ee2e45b1fedb1b4b4ca1 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 7 Oct 2015 15:43:31 -0700 Subject: [PATCH] documentation: Composability analogies This commit expands on RCU's composability by comparing it to that of transactional memory and of locking. Signed-off-by: Paul E. McKenney --- Documentation/RCU/Design/Requirements/Requirements.html | 8 ++++++++ Documentation/RCU/Design/Requirements/Requirements.htmlx | 8 ++++++++ 2 files changed, 16 insertions(+) diff --git a/Documentation/RCU/Design/Requirements/Requirements.html b/Documentation/RCU/Design/Requirements/Requirements.html index cc5b587c0ec5..105247149975 100644 --- a/Documentation/RCU/Design/Requirements/Requirements.html +++ b/Documentation/RCU/Design/Requirements/Requirements.html @@ -1494,6 +1494,14 @@ in RCU implicitly splitting the enclosing RCU read-side critical section, neither of which is conducive to a long-lived and prosperous kernel. +

+It is worth noting that RCU is not alone in limiting composability. +For example, many transactional-memory implementations prohibit +composing a pair of transactions separated by an irrevocable +operation (for example, a network receive operation). +For another example, lock-based critical sections can be composed +surprisingly freely, but only if deadlock is avoided. +

In short, although RCU read-side critical sections are highly composable, care is required in some situations, just as is the case for any other diff --git a/Documentation/RCU/Design/Requirements/Requirements.htmlx b/Documentation/RCU/Design/Requirements/Requirements.htmlx index 23524d75a3c3..5b76e21fa092 100644 --- a/Documentation/RCU/Design/Requirements/Requirements.htmlx +++ b/Documentation/RCU/Design/Requirements/Requirements.htmlx @@ -1653,6 +1653,14 @@ in RCU implicitly splitting the enclosing RCU read-side critical section, neither of which is conducive to a long-lived and prosperous kernel. +

+It is worth noting that RCU is not alone in limiting composability. +For example, many transactional-memory implementations prohibit +composing a pair of transactions separated by an irrevocable +operation (for example, a network receive operation). +For another example, lock-based critical sections can be composed +surprisingly freely, but only if deadlock is avoided. +

In short, although RCU read-side critical sections are highly composable, care is required in some situations, just as is the case for any other -- 2.20.1