> Taking the lock is going to transiation the cacheline to exclusive. If > the next locker tries to take the lock, they transfer the cacheline and > exclusive access and fail. If they have already tried to take the lock > earlier, they might only request a readonly state, but it still requires > a cacheline transfer (which is the expensive part). the "which is the expensive part" isn't entirely true on modern hardware (and for sure not on multicore systems); due to various bus snooping tricks and other "pass-the-cacheline" tricks this is relatively cheap; not free obviously but not nearly as expensive as the exclusive part. - 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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