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| author | Davidlohr Bueso <davidlohr@hp.com> | 2014-07-30 13:41:56 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2014-08-13 10:32:04 +0200 |
| commit | 0a7cbf9abe3198461de3d3e97268db32a646ba06 (patch) | |
| tree | 0e071f305840ba9aff93d16981963fa0cbcf09ba /Documentation/locking | |
| parent | 214e0aed639ef40987bf6159fad303171a6de31e (diff) | |
| download | op-kernel-dev-0a7cbf9abe3198461de3d3e97268db32a646ba06.zip op-kernel-dev-0a7cbf9abe3198461de3d3e97268db32a646ba06.tar.gz | |
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.txt | 6 |
1 files 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 ------------------- |
