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authorPaul E. McKenney <paulmck@us.ibm.com>2006-02-01 03:06:42 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-01 08:53:25 -0800
commitd19720a909b4443f78cbb03f4f090180e143ad9d (patch)
tree56e579612d82f4b30d5cb943df1079b0b5f4700a /Documentation/RCU/RTFP.txt
parent53d8be5c144ece5d48745810b14248968e73eaf2 (diff)
downloadlinux-linaro-stable-d19720a909b4443f78cbb03f4f090180e143ad9d.tar.gz
[PATCH] RCU documentation fixes (January 2006 update)
Updates to in-tree RCU documentation based on comments over the past few months. 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/RTFP.txt')
-rw-r--r--Documentation/RCU/RTFP.txt25
1 files changed, 14 insertions, 11 deletions
diff --git a/Documentation/RCU/RTFP.txt b/Documentation/RCU/RTFP.txt
index fcbcbc35b122..6221464d1a7e 100644
--- a/Documentation/RCU/RTFP.txt
+++ b/Documentation/RCU/RTFP.txt
@@ -90,16 +90,20 @@ at OLS. The resulting abundance of RCU patches was presented the
following year [McKenney02a], and use of RCU in dcache was first
described that same year [Linder02a].
-Also in 2002, Michael [Michael02b,Michael02a] presented techniques
-that defer the destruction of data structures to simplify non-blocking
-synchronization (wait-free synchronization, lock-free synchronization,
-and obstruction-free synchronization are all examples of non-blocking
-synchronization). In particular, this technique eliminates locking,
-reduces contention, reduces memory latency for readers, and parallelizes
-pipeline stalls and memory latency for writers. However, these
-techniques still impose significant read-side overhead in the form of
-memory barriers. Researchers at Sun worked along similar lines in the
-same timeframe [HerlihyLM02,HerlihyLMS03].
+Also in 2002, Michael [Michael02b,Michael02a] presented "hazard-pointer"
+techniques that defer the destruction of data structures to simplify
+non-blocking synchronization (wait-free synchronization, lock-free
+synchronization, and obstruction-free synchronization are all examples of
+non-blocking synchronization). In particular, this technique eliminates
+locking, reduces contention, reduces memory latency for readers, and
+parallelizes pipeline stalls and memory latency for writers. However,
+these techniques still impose significant read-side overhead in the
+form of memory barriers. Researchers at Sun worked along similar lines
+in the same timeframe [HerlihyLM02,HerlihyLMS03]. These techniques
+can be thought of as inside-out reference counts, where the count is
+represented by the number of hazard pointers referencing a given data
+structure (rather than the more conventional counter field within the
+data structure itself).
In 2003, the K42 group described how RCU could be used to create
hot-pluggable implementations of operating-system functions. Later that
@@ -113,7 +117,6 @@ number of operating-system kernels [PaulEdwardMcKenneyPhD], a paper
describing how to make RCU safe for soft-realtime applications [Sarma04c],
and a paper describing SELinux performance with RCU [JamesMorris04b].
-
2005 has seen further adaptation of RCU to realtime use, permitting
preemption of RCU realtime critical sections [PaulMcKenney05a,
PaulMcKenney05b].