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> The request itself has been > touched by scsi_end_request() already, so unless the layout is really > bad we shouldn't need to fetch a lot of cache lines there. That leaves > __test_and_clear_bit(), I guess that must be it. __test_and_clear_bit() is cheap; it's a single non-locked instruction. Arguably it should be converted into a C variant so that the compiler can pick the best code sequence (I'm not so sure the asm we picked for this is optimal for all processors, I bet it'll be microcoded) but I'd be surprised if it'd be more than a handful of cycles no matter what. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org 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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