Messages in this thread | | | Date | Wed, 01 Sep 2004 11:30:26 -0400 | From | Mark Lord <> | Subject | Re: [PATCH] Configure IDE probe delays |
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>> I haven't examined the "released" IDE drivers in some time, >> but one optimisation that can save a LOT of CPU usage >> is for the driver to only use LBA48 *when necessary*, >> and use LBA28 I/O otherwise. >> >> Each access to an IDE register typically chews up 600+ns, >> or the equivalent of a couple thousand instruction executions >> on a modern core. Avoiding LBA48 when it's not needed will >> save four such accesses per I/O, or about 2.5us.
Yup, this is for ATA register accesses, not SATA FISs. -- Mark Lord (hdparm keeper & the original "Linux IDE Guy") - 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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