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

[Andrew Morton]

Adrian Bunk <bunk@xxxxxxxxx> wrote:
>
> On Sat, Oct 18, 2003 at 10:24:02AM -0700, Andrew Morton wrote:
> > "Martin J. Bligh" <mbligh@xxxxxxxxxxx> wrote:
> > >
> > > Please don't - I benchmarked it a while ago, and it's definitely slower.
> > 
> > Alan said he generally found -Os to be faster...
> 
> Not exactly:
>   http://www.ussg.iu.edu/hypermail/linux/kernel/0211.0/1513.html
> 

http://www.ussg.iu.edu/hypermail/linux/kernel/0308.1/1261.html

And bear in mind that you can see significant changes in benchmark results
between equivalent kernels even when the optimisation level is kept the
same, due to aliasing and alignment luck.

It would take a quite a lot of work to measure this properly.  A simple A/B
comparison doesn't cut it.

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