FORTIFY_SOURCE for the kernel

sean seanlkml at sympatico.ca
Mon Jan 23 16:38:19 UTC 2006


On Mon, 23 Jan 2006 17:31:01 +0100
Ralf Corsepius <rc040203 at freenet.de> wrote:

> > -Os is undeniably good for 2), most likely to the point where it beats
> > performance.
> That exactly is the question!
> 
> The subsequent one would be: Where is the origin?
> 

This has already been answered in previous responses.   Modern processors are
so much faster than memory and other subsystems that cache misses destroy
most benefits of loop unrolling and other -02 "speed" optimizations that
were more appropriate for older systems.   Using -0s ends up generating
code which has the best chance of reducing cache misses and thus ends up
being faster as well as smaller.

Sean




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