Re: [2.6 patch] add a config option for -Os compilation

[Jan-Benedict Glaw <jbglaw@lug-owl.de>]

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On Sat, 2003-10-18 12:21:27 +0200, Adrian Bunk <bunk@fs.tum.de>
wrote in message <20031018102127.GE12423@fs.tum.de>:
> On Wed, Oct 15, 2003 at 04:52:05PM -0700, Andrew Morton wrote:
> > I really doubt it.  Kernel CPU footprint is dominated by dcache misses.  If
> > -Os reduces icache footprint it may even be a net win; people tend to
> > benchmark things in tight loops, which favours fast code over small code.
> 
> The main effect of -Os compared to -O2 (besides disabling some
> reordering of the code and prefetching) is the disabling of various
> alignments. I doubt that's a win on all CPUs.

I definively *like* to see -Os be configureable by user. It's *big* win
for a lowmem system. There, the actual "running speed" may be limited by
HDD swap speed, and having a smaller kernel means having more pages left
to luserspace...

MfG, JBG

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