tulip vs. Lite On

Mark Hahn hahn@coffee.psychology.mcmaster.ca
Wed Dec 9 00:10:15 1998

> however be fixed. If you bump up your CACHELINE / Burst size values (PCI CACHELINE 
> / CSR0), you will be able to get the Lite-On to perform just as good as the 21143.

what values do you suggest?

the current tulip driver chooses 8 longword cache alignment, 8 lw bursts
if the driver is modular or on sub-P5's.  or 16 longword alignment and 
unlimited bursts on P5's and better.  this seems a little odd to me,
since these are twice the real cache sizes, if a longword is 32b:
cache lines are 16B on 486, 32B on >=P5.

perhaps the tests were run on a modular kernel; that would select relatively
short bursts.  It would be valuable to hear about the results with difference
alignment/burst values.  if "longword" means 32b, a P5/P6/PII should have 
0x4000 set for cache alignment; I don't know why Donald chose unlimited
bursts for >=P5, but only 8-longword bursts for the 486.
(and 32 lw on Alpha, and unlimited on PPC.)

regards, mark hahn.