[tip:locking/core] locking/Documentation: Update locking/ mutex-design.txt disadvantages

[tip-bot for Davidlohr Bueso]

Commit-ID:  0a7cbf9abe3198461de3d3e97268db32a646ba06
Gitweb:     http://git.kernel.org/tip/0a7cbf9abe3198461de3d3e97268db32a646ba06
Author:     Davidlohr Bueso <davidlohr@xxxxxx>
AuthorDate: Wed, 30 Jul 2014 13:41:56 -0700
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 13 Aug 2014 10:32:04 +0200

locking/Documentation: Update locking/mutex-design.txt disadvantages

Fortunately Jason was able to reduce some of the overhead we
had introduced in the original rwsem optimistic spinning -
an it is now the same size as mutexes. Update the documentation
accordingly.

Signed-off-by: Davidlohr Bueso <davidlohr@xxxxxx>
Acked-by: Jason Low <jason.low2@xxxxxx>
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: aswin@xxxxxx
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1406752916-3341-7-git-send-email-davidlohr@xxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 Documentation/locking/mutex-design.txt | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Documentation/locking/mutex-design.txt b/Documentation/locking/mutex-design.txt
index ee231ed..60c482d 100644
--- a/Documentation/locking/mutex-design.txt
+++ b/Documentation/locking/mutex-design.txt
@@ -145,9 +145,9 @@ Disadvantages
 
 Unlike its original design and purpose, 'struct mutex' is larger than
 most locks in the kernel. E.g: on x86-64 it is 40 bytes, almost twice
-as large as 'struct semaphore' (24 bytes) and 8 bytes shy of the
-'struct rw_semaphore' variant. Larger structure sizes mean more CPU
-cache and memory footprint.
+as large as 'struct semaphore' (24 bytes) and tied, along with rwsems,
+for the largest lock in the kernel. Larger structure sizes mean more
+CPU cache and memory footprint.
 
 When to use mutexes
 -------------------
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