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authorDavidlohr Bueso <davidlohr@hp.com>2014-07-30 13:41:56 -0700
committerIngo Molnar <mingo@kernel.org>2014-08-13 10:32:04 +0200
commit0a7cbf9abe3198461de3d3e97268db32a646ba06 (patch)
tree0e071f305840ba9aff93d16981963fa0cbcf09ba /Documentation/locking
parent214e0aed639ef40987bf6159fad303171a6de31e (diff)
downloadblackbird-op-linux-0a7cbf9abe3198461de3d3e97268db32a646ba06.tar.gz
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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@hp.com> Acked-by: Jason Low <jason.low2@hp.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: aswin@hp.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Randy Dunlap <rdunlap@infradead.org> Link: http://lkml.kernel.org/r/1406752916-3341-7-git-send-email-davidlohr@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation/locking')
-rw-r--r--Documentation/locking/mutex-design.txt6
1 files changed, 3 insertions, 3 deletions
diff --git a/Documentation/locking/mutex-design.txt b/Documentation/locking/mutex-design.txt
index ee231ed09ec6..60c482df1a38 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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