Re: -O2 vs -O3

Date: Wed May 24 2000 - 14:21:41 EST

On Wed, May 24, 2000 at 09:48:19AM -0600, Christopher Thompson wrote:
> Brief question:
> Linux kernels are compiled with the -O2 flag set. I'm curious, why don't we
> use -O3?

-O3 introduces some optimisations which may not be appropriate for the
kernel. In particular, it tries to know better about function-inlining.
It is asserted (note I don't necessarily agree with the assertion :-)
that the kernel developers in their infinite wisdom have analysed which
functions would best be inlined and which are best out-of-line.

> Also, is it now safe to compile the 2.3.99-prex kernels with gcc 2.95.2 instead
> of

not sure. most people seem to, but if you run into any problems, it's
normally advised that you should drop back to 2.7.2 to verify them.

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