Subject: Re: your mail
To: Matthew Jacob <>
From: Manuel Bouyer <>
List: current-users
Date: 08/27/2000 21:46:01
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.