Re: Mechanism to configure default scheduling model on PA

[law at redhat dot com]

In message <200205310413.g4V4DEGh004261@hiauly1.hia.nrc.ca>, "John David Anglin
" writes:
 > The default scheduling model was changed recently from that for the 7100
 > processor to that for the 8000 processors.  This change was not particularly
 > suitable for older hardware.
 > 
 > This patch introduces a mechanism to configure the default scheduling
 > model.  The 700 model is used for pa1.0 targets, the 7100 model is
 > used for pa1.1 targets, and the 8000 model is used for all other
 > targets (ie., it's still the default).  The sophisticated user
 > can define TARGET_SCHED_DEFAULT in BOOT_CFLAGS if some other default
 > is desired.
 > 
 > The patch has been tested on hppa1.1-hp-hpux10.20, hppa2.0w-hp-hpux11.11
 > and hppa-linux.
Thanks.  I've always thought about doing this, but figured it wasn't
worth the time.

If you wanted to get more correct, then you'd look at the actual
model # and map that into 700, 7100, 7100lc, 7200, 7300 or 8000.

FWIW, PA700 is actually the first generation PA1.1 machines -- we never
bothered writing descriptions for the original PA1.0 machines.  It's also
the case that the previous default was 7100LC, not 7100.

So what I might recommend would be to use PA8000 for PA2.0 and newer and
PA7100LC for the others.

PA7100LC scheduling works very well on the PA7100LC, PA7200 and PA7300 class
machines (they only differ in their handling of store-load and store-store
penalties).  PA7100LC also works reasonably well for PA7100 and PA700 machines.

jeff