[parisc-linux] 715 useful

Grant Grundler grundler@cup.hp.com
Sun, 14 Nov 1999 19:57:05 -0800

"John David Anglin" wrote:
> > For the machines which have ASP, am I right in saying they have no other
> > sources of interrupts?  ie what I want to do is:
> Under hpux 10.X, I was told that the NCR 710/720 controller devices are
> sources of interrupts.  They do this by writing to the processor.  Thus,
> it appears they bypass the ASP.

As noted later, I was the source of John's information.
More notes:

o This is a the HP-UX c720 driver taking advantage of the architecture.
  Linux SCSI drivers won't do that (yet).

o Alex misunderstood - the HP-UX c720 driver *can* bypass all line
  based interrupt support (ASP/LASI/Dino/...). It only does it for
  a card which already uses transaction based interupts (TBIs)
  (HSC F/W SCSI). TBIs are required to work on HSC bus to meet
  PA I/O Arch and the c720 driver was coded with this safe assumption.
  TBIs sadly do NOT work under PCI on all platforms.

o Someone also already pointed out the timer uses the processor
  interrupts. I don't know if WAX (EISA) has it's own IAR but
  would expect it too. My advice: boot HP-UX 10.20 or 11.X,
  run Q4 and include pa_intr.pl, "run DumpEIRR" and you'll see
  exactly which EIR bits are used.

o and lastly, I too am skeptical (like Philipp) how useful this
  optimization is. I can help measure it once the box is running.
  I have my own set of optimizations I *think* we need. Philipp
  agreed we would put them in once I had measurements showing
  the improvement.


Grant Grundler
Unix Developement Lab