Re: K6 patches for review

[Jeffrey A Law <law at cygnus dot com>]

  In message <199808221758.KAA06341@dm.cobaltmicro.com>you write:
  >    From: John Carr <jfc@tiac.net>
  >    Date: Sat, 22 Aug 1998 09:46:34 EDT
  > 
  >    Please comment.
  > 
  >    This patch adds AMD K6 optimizations, based on AMD publication 21924B
  >    for the K6-2.  I don't know if the K6 pipeline is significantly
  >    different.  I have not run benchmarks yet.
  > 
  > You will get more profitable results if you use a slotting scheme like
  > I did on the UltraSparc using the MD_SCHED macros.  Haifa is really
  > dumb.  Haifa never got quad issue on Ultra before my hacks, I simply
  > couldn't describe the chip using the current define_function_unit
  > scheme, now for FPU code Haifa gets quad issue often.  ADJUST_COST is
  > yet another hack that doesn't work at all...
I'd argue with "doesn't work at all...".   It's value as diminished
over time as superscalar machines have become popular.

MD_SCHED is the way to go right now.  There's serveral things I want
to describe for the PA using MD_SCHED when I get the chance.  Presumably
as we get a better feel for the kinds of problems everyone uses MD_SCHED 
to solve we'll have a better clue what kinds of things we need to do
in the generic scheduler :-)

jeff