On Sun, Aug 27, 2000 at 12:36:07PM -0700, Matthew Jacob wrote:
> 
> > BTW, tagged queuing on IDE will increase the interrupt load and IDE command
> > latency significantly, I'm not sure it will increase the overall performances
> > in all cases :)
> 
> That's always the case. 
> 

Yes, I noticed this for SCSI (it's the disconnect/reselect, rather than
command queuing, which is the killer). But most scsi controllers are 
intelligent these days, and the complexity overhead is mostly handled by the
controller; from a CPU point of view it's mostly a latency overhead.
With IDE, the CPU will have to do all the work. So we'll have more latency,
and more CPU time spent in interrupt handlers. But I think it's worth it,
with eventually a way to disable it.

--
Manuel Bouyer, LIP6, Universite Paris VI.           Manuel.Bouyer@lip6.fr
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