On Sat, Dec 17, 2005 at 12:01:27AM +1100, Nick Piggin wrote: > You were proposing a worse default, which is the reason I suggested it. I'd like to qualify that. "for architectures with native cmpxchg". For general consumption (not specifically related to mutex stuff)... For architectures with llsc, sequences stuch as: load modify cmpxchg are inefficient because they have to be implemented as: load modify load compare store conditional Now, if we consider using llsc as the basis of atomic operations: load modify store conditional and for cmpxchg-based architectures: load modify cmpxchg Notice that the cmpxchg-based case does _not_ get any worse - in fact it's exactly identical. Note, however, that the llsc case becomes more efficient. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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