[9fans] DPT PM2041W observations

[Eric Dorman eld@jewel.ucsd.edu]

> Date: Mon, 12 Jan 1998 13:58:43 -0600
> From: "G. David Butler" <gdb@dbSystems.com>
> To: 9fans@cse.psu.edu
> Subject: Re: [9fans] DPT PM2041W observations
> 
> >If the answer to that is "yes, with Tag Queueing", then I
> >need some kind soul to help me get that to happen on the
> >DPT adapter.  (The 154x can't do that.)  None of the
> >documentation or source I have enable that feature.
> 
> I found and read the relevant parts of the SCSI-2 spec.
> I now have tag queueing working.  I also found the DPO flag
> which helps both cards.  Now the 154x does 1460MB/s (2% isn't
> much, but anything helps.)

Cool.  Patch?

> So why does this 4th generation card with tag queueing support
> run slower than the 1st generation design that is over 10 years
> old?

Perhaps the driver for the 1540 is better optimized as it's been
around longer, and it's had more work put into it.  There might
be something in the DPT documentation that one can do with the 
card that one can't do with a 1540 ( bus on/off? ).  1540 is a
well-developed and understood card, whereas most other stuff
isin't nearly as common.

> David Butler
> gdb@dbSystems.com

Regards,

Eric Dorman
edorman@ucsd.edu