RFC: Optimizing for 386 (Part 2)

[Peter Jones]

On Fri, 2005-03-25 at 09:34 -0600, Derek Moore wrote:
[Sean's text skipped]
> There's no need to be a prick in public.

Oh please, read what he's responding to.

On Thu, 2005-03-24 at 23:56 -0600, Joseph Wagner wrote:
> Hello Linux Naysayers!

No comment.

> You may remember about two months ago I started a flame war asking why RPM 
> packages were still optimized for 386.  The best answer I heard said that 
> the powers-that-be do not believe there would be a noticeable improvement, 
> and if I wanted to affect real change I would need to prove them wrong.

As I recall, the best answers were that we do optimize for newer cpus,
we just don't use the compiler flag which tells gcc to generate _one
more instruction_ (!) which would make the binaries unusable on older
processors.  Where that one instruction would makes a significant
difference, we build target-specific packages, such as we do with glibc
and the kernel.

It's also been mentioned that several packages include hand-coded
assembly which uses many more features of newer cpus than would code
generated by gcc with different optimization options.  Those routines
are typically selected at runtime, meaning the packages themselves are
still for the i386 arch.

On Fri, 2005-03-25 at 09:34 -0600, Derek Moore wrote:
> He's not the only one that believes compiler optimizations have an
> effect at runtime (if he was, Gentoo wouldn't exist).

No, he's not the only one of this opinion, but he is the one clearly
ignoring the relevant threads on the subject.

It's really easy to be very frustrated on this subject.  In the presence
of clear and useful information as to the reasoning for the choice of
the CFLAGS used in Fedora, we have to ignorant people slamming the right
decisions again and again and again.

> Now that he's done the hard part of rebuilding the distro

That's really not the hard part.  At worst, it's the *slow* part.  See,
we ship the distro with these things called "source rpms", and they're
pretty neat.  They include instructions on how to build themselves, and
we also provide tools that can use those instructions to automatically
build *for* you!

-- 
        Peter