Subject: Re: siop(4) and tagged queuing
To: Manuel Bouyer <>
From: Matthew Jacob <>
List: current-users
Date: 10/23/2000 10:30:46
> > Be careful about removing this. OpenBSD did this recently with amusing
> > breakage.
> > 
> > The midlayer needs to be a lot smarter about job scheduling so that it
> > respects an HBA's openings limit and also w/o letting one spindle saturate a
> > system but also w/o artificially limiting things.
> Yes, for sure. BTW, siop currently only allows 15 tags per device.
> I'm not sure allowing an arbitrary number of commands to be queued would
> be a good idea; it could take several seconds for the queue to drain.

SPI allows for 256 tags. Manage the limit unless it desperately costs you.

Your typical disk drive will manage at least 64 tags these days w/o sending
back QFULL.