Re: [PATCH] take 48-bit lba a bit further

Alan Cox (alan@lxorguk.ukuu.org.uk)
06 Apr 2003 15:35:25 +0100


On Sul, 2003-04-06 at 14:32, John Bradford wrote:
> Then, don't we want to be using 48-bit lba all the time on compatible devices
> instead of falling back to 28-bit when possible to save a small amount of
> instruction overhead? (Or is that what we're doing already? I haven't really
> had the time to follow this thread).

The overhead of the double load of the command registers is microseconds so it
is actually quite a lot, especially since IDE lacks TCQ so neither end of the
link is doing *anything* useful. SCSI has similar problems on older SCSI with
command sending being slow, but the drive is at least doing other commands during
this.

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