Subject: Re: comments on i386 -1.2BETA snapshot
To: Jason Thorpe <>
From: Justin T. Gibbs <>
List: port-i386
Date: 08/27/1996 19:35:04
>On Tue, 27 Aug 1996 08:31:40 -0700 
> "Justin T. Gibbs" <> wrote:
>[ Jukka sez... ]
> > >Is there any hope of improvement in the future?  This is a real problem
> > >for us.  CCD is just great, especially on news servers, but the SCSI
> > >driver problems limit the number of disks to two. :-(
>Let's be a little more clear, here... The problem is that come models of 
>the Adaptec controller (aic7xxx-family) have a rediculously small amount 
>of RAM on them, limiting the number of commands they can concurrently 
>process.  Under high-load conditions (which isn't much load, 
>unfortunately, on these controllers), the NetBSD MI SCSI subsystem is 
>unable to queue commands on these controllers due to resource shortage...

The Aic7xxx cards help manifest this problem, but they are not the cause of
the problem.  The buslogic driver would also show this problem if tagged
queueing was implemented.  You can bag on the aic7xxx cards all you want, but
broken software is broken software.

> -- save the ancient forests - -- 
>Jason R. Thorpe                             
>NASA Ames Research Center                               Home: 408.866.1912
>NAS: M/S 258-6                                          Work: 415.604.0935
>Moffett Field, CA 94035                                Pager: 415.428.6939

Justin T. Gibbs
  FreeBSD: Turning PCs into workstations