Optimizationn questions?

Gary Kline kline at tao.thought.org
Fri Mar 16 03:44:14 UTC 2007

On Thu, Mar 15, 2007 at 08:25:43PM -0700, Garrett Cooper wrote:
> Gary Kline wrote:
> >On Wed, Mar 14, 2007 at 08:19:49PM -0700, youshi10 at u.washington.edu wrote:
> >>On Thu, 15 Mar 2007, Danny Pansters wrote:
> >>
> No problem. -funroll-loops might not buy you too much other than a few 
> less instructions overall but I'm not sure how intelligent gcc is at 
> unrolling loops. It seemed like there was a difference between 
> optimizations in the 4.x branch compared to the 3.4.x sub branch. They 
> made a lot of improvements in the 4.x branch though.. it's just that 
> some of those improvements broke code, so that's probably why FreeBSD 
> doesn't have gcc-4.x in the base system.

	Until one of my hardware buddes can swap memory from an unsed
	Kayak into my "new" (koff-koff) one, I have to be careful about 
	the added bytes that loop unrolling costs.  It's ballpark 10%
	with the default gcc.  I'm building the 4.x stuff now with no
	++CFLAGS.  The compiler guys know their stuff.  If any good and
	surprising news happens, I'll post it.  "Unix: get every last
	billionth-of-a-penny's worth out of your hardware."   ah, life!


> Cheers :).
> -Garrett
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  Gary Kline  kline at thought.org   www.thought.org  Public Service Unix

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