Safe (but quick) GCC settings on a PC64 with 5.3?

Kirk Strauser kirk at strauser.com
Mon Dec 13 09:31:03 PST 2004


I just upgraded a little PC64 from FreeBSD 4.10 to 5.3 via the installer 
ISO.  First, I'd like to send my gratitude and appreciation to everyone who 
helped on the Alpha port; the upgrade was a piece of cake and worked 
perfectly from the first boot.

Anyway, I'm planning to rebuild all of my ports to take advantage of GCC's 
new optimizations (versus the old 2.95 version they'd been previously built 
with) and the kernel to try to wring a little more performance out of this 
small system whose dmesg starts with:

  Copyright (c) 1992-2004 The FreeBSD Project.
  Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
          The Regents of the University of California. All rights reserved.
  FreeBSD 5.3-STABLE #0: Sun Dec 12 22:31:54 CST 2004
      root at gopher.honeypot.net:/usr/obj/usr/src/sys/NEW_GOPHER
  EB64+
  Digital AlphaPC 64 274 MHz, 274MHz
  8192 byte page size, 1 processor.
  CPU: EV45 (21064A) major=6 minor=2
  OSF PAL rev: 0x100040002012d
  real memory  = 266346496 (254 MB)
  avail memory = 250544128 (238 MB)
  apecs0: <DECchip 21072 Core Logic chipset>

I currently have these in my /etc/make.conf:

  CPUTYPE=ev45
  CFLAGS= -O -pipe -mieee
  COPTFLAGS= -O -pipe

I have *no* desire to make an unstable system in an attempt to squeeze out 
that last 0.2% of performance.  On the other hand, this box isn't exactly a 
speed demon and every little bit can make a noticeable difference.  If I 
can get an extra 10% at the cost of a lengthy recompile, I'll jump at the 
chance.

I have much more experience with x86 and Sparc systems than Alpha, and I'm 
not really sure what else I should or could have in there.  I've read the 
"DEC Alpha Options" section of GCC manual, but I don't have the experience 
to know whether things like '-mno-soft-float' are good or bad, or whether I 
should be mucking around with '-mmemory-latency'.  This is where I could 
really use a bit of guidance.

Many thanks!
-- 
Kirk Strauser
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