Re: [gentoo-amd64] Re: Re: Giving up 64 platform

[Brandon Edens]

On Tue, Apr 25, 2006 at 01:59:47AM -0700, Duncan wrote:

> That's also why I tend to favor -Os and certain other similar
> optimizations (I add various register re-use and hot/cold function
> reordering flags as well, as the register optimizations will be very good
> for amd64, even at the cost of code size, and hot/cold function reordering
> regroups functions such that the frequently used ones stay in cache
> better, even at the expense of overall code size). Smaller code, given
> memory latencies, should be faster code, even if it's less efficient at
> the CPU itself, because that much more of the code fits in the next closer
> level of cache, that would otherwise be in far slower memory or cache
> futher from the CPU.

Thats interesting stuff Duncan. I've been looking for details regarding gcc's
possible optimizations for AMD64 along with low-level details of what they do.
Are you using gcc 3 or 4? Is there much work to be done, porting AMD64
optimizations from 3 to 4's tree stuff? I'd like to read more or know where to
find additional info.

> That said, performance is one thing, human frustration is an entirely
> different thing.  Because the (desktop/workstatiion) computer spends most
> of its time waiting for human input, an efficient human/computer interface
> is a far more important factor than all the others.  Of course, one
> person's richly efficient interface is another's bloat, making it
> virtually impossible to benchmark.
>
> The reason I suggested going back to regular x86 Gentoo in this case is
> that it's quite apparent there's a lot of friction in that computer/human
> interface at present, and for him, x86 may just work best, at the moment.
> While it makes us geek types cringe at the supposed resource waste, is he
> actually wasting more /not/ using AMD64 because he's too frustrated with
> it, or smoothly using x86, which he knows and is comfortable with? There's
> nothing "wrong" wth using it in x86 mode, and if that's what suits is
> style best, then more power to him (literally, more power over the
> computer)!
>
> The thing is, it's his decision, not your or mine.  He's the one living
> with the consequences.  If he's more comfortable on x86, and all amd64 is
> giving him is frustration, then x86 is the way he should go.  If he
> believes he can pull it out with the help of a chroot or the like, then
> let him try, but don't force it on him, and don't make him so despairing
> he quits Gentoo in frustration, when he's already said he's very
> comfortable with x86 Gentoo.

You're totally correct. I've installed x86 on quite a few AMD64 machines for
friends that aren't extremely savvy. Gentoo neophytes shouldn't have to deal
with the headaches AMD64 sometimes brings. If the users are high-performance
computing types well...  I wasn't attempting to pressure him into using AMD64.
Only to further elucidate the situation. Hoping that further education on the
issue would aid in making decisions.

Brandon