Re: [Lse-tech] Re: gcc 2.95 vs 3.21 performance

Dipankar Sarma
2003-02-05T12:58:01Z

On Wed, Feb 05, 2003 at 01:41:34PM +0200, Denis Vlasenko wrote:
> My argument was against overusing optimization techniques.
> You cannot speed up kernel by aligning *everything* to 32 bytes,
> or by unrolling all loops, or by aggressive inlining.
> That's too easy to work. You get kernel which is bigger
> *and* slower.

I am not getting into this debate, just wanted to point out that
effect of compiler optimization on UNIX kernels have been studied
before. One paper I recall is -

http://www.usenix.org/publications/library/proceedings/sf94/full_papers/partridge.ps

They used prfile-guided optimization, so that is whole another angle altogether.

Thanks
Dipankar