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authorNick Piggin <npiggin@suse.de>2008-10-21 04:59:15 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-23 12:18:20 -0400
commita8ddac7e53e89cb877965097d05adfeb1c91def3 (patch)
treedb4ee686e50f7fb57b0cef20e0a8e7f06151e317 /lib/reciprocal_div.c
parent5a439c565799cb8d290d71ce375e86be64d43a4b (diff)
mutex: speed up generic mutex implementations
- atomic operations which both modify the variable and return something imply full smp memory barriers before and after the memory operations involved (failing atomic_cmpxchg, atomic_add_unless, etc don't imply a barrier because they don't modify the target). See Documentation/atomic_ops.txt. So remove extra barriers and branches. - All architectures support atomic_cmpxchg. This has no relation to __HAVE_ARCH_CMPXCHG. We can just take the atomic_cmpxchg path unconditionally This reduces a simple single threaded fastpath lock+unlock test from 590 cycles to 203 cycles on a ppc970 system. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/reciprocal_div.c')
0 files changed, 0 insertions, 0 deletions