Tue, 18 Jul 2000 17:01:02 -0700 (PDT)
On Tue, 18 Jul 2000, Matthew Wilcox wrote:
> i can't seem to find any documentation on the HP website about scheduling
> instructions for different processor models.
There are at least two processor model docs
on the puffin site (PCXL and PCXL2, i.e. the 7100LC and 7300 I believe).
These ERSs discuss pipelines, latencies, bundling rules, etc -- scheduling
> gcc currently defaults to
> scheduling for the PA700 (presumably this is PCX?), and can be asked
> to schedule for PA-7100, PA-7200 or PA-8000.
PCXT = 7100
PCXT' = 7200
PCXU = 8000
> i'm guessing that 8200,
> 8500 and 8600 have slightly different scheduling requirements.
The 8200, 8500, and 8600 have the same basic core as the PA8000. Scheduling
for the 8000 should be fine for 8x00.
> my main question is, what should we default it to? does scheduling for
> PA-8000 have a really bad effect on other CPU models? or vice versa,
> is scheduling for PA-700 a really bad choice for PA-8x00 CPUs?
> i know
> later PA models have all the fancy register renaming stuff in them so
> it may not make much difference, but i'm curious.
While it would be cool to have a kernel specifically scheduled for
each processor, its likely that one will just have to be chosen for
a 32-bit kernel.
The PA8x000 are probably the least susceptible to other schedules
because of its ROB. Scheduling for 7100 or 7200 might be a good choice
(or whatever machine seems to be the most popular).
Obviously, a 64-bit kernel (when it exists) would best be
scheduled as PA8000.