Re: [PATCH] Configure IDE probe delays

Mark Lord
2004-09-01T15:37:11Z

>> 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")