Kevin Kofler wrote:
Callum Lerwick wrote:
> Going -O3 rather than -O2 is going to make a bigger difference than
> anything else. If you want to improve performance, you need to run
> profiles, locate performance critical bits of code, figure out if -O3 is
> beneficial, and/or write some hand tuned assembly/intrinsic code.
>
> Not to mention, the biggest performance problem on modern processors is
> memory. Minimizing cache thrashing is way more important than what
> instructions you use. Optimize data structures before code.
That's actually an argument for investigating -Os, not -O3.
Kevin Kofler
In 2004 there were some experiments performed by some NCSU students on the
effect of -Os on code size and performance:
people.redhat.com/wcohen/ncsu2004/Space%20Optimizations.pdf
There was some minor reductions in cache misses, major page faults, and startup
times for the mozilla application.
-Will