[9fans] DPT PM2041W observations

[Eric Dorman eld@jewel.ucsd.edu]

Gdb wrote:
> Date: Mon, 12 Jan 1998 14:52:37 -0600
> From: "G. David Butler" <gdb@dbSystems.com>
 
> >> 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
> Remember, I have written both drivers from scratch and each
> is optimized for the controller it is talking to.

  Is it?  I gathered from your original post that your guide was 
the BSDi DPT driver, and teaching the 154x driver to talk to the 
DPT; the DPT docs weren't mentioned..  Is the BSDi driver considered 
definative?

  Historically I vaguely recall the DPT ppl claiming their card 
was 'faster' than a 154x, but that may be only for certain subsets 
of problems.  DPT may be interested in discovering why, for this 
test, it apparently loses out.. then again, as PCI has supplanted 
ISA for this application, maybe not.  

  Do you have a caching module?  It may be that w/o one the card 
isin't a win.  The caching might also take advantage of a request
distribution similar to the usual Micro$sloth stuff which isin't
valid for Plan9.
 
> David Butler
> gdb@dbSystems.com

Regards,

Eric Dorman
edorman@ucsd.edu