[gentoo-amd64] Re: 64 or 32?

[Duncan]

Thierry de Coulon posted <200602100035.08352.tcoulon@××××××××.ch>,
excerpted below,  on Fri, 10 Feb 2006 00:35:08 +0000:

> Hello,
>
> I'm testing several distributions on my new dual-opteron. I did a gentoo-64
> install - and managed to screw it up, but this was expected as I was testing.
> I have confirmed that I dislike (k)ubuntu for several reasons, either 64 or
> 32 bit. SuSE 64 hasn't impressed me either. I have managed to install Simply
> Mepis (32bit) and compile an Opteron kernel and it works well.

Gratifying that Gentoo has impressed you enough to continue with it, after
having rejected most of the other distributions.

> So I am thinking that a 32bit Gentoo is the way to go. I may switch to
> 64bit later, when it really (?) brings something
>
> Does anyone have other arguments to justify the troubles of working with
> a 64bit install at the moment?

The others have dealt with the specific apps you mentioned, so I'll do an
overview, which seems somewhat missing in most of the posts so far.

Technically, amd64 does very well in 32-bit mode, so there's no reason to
run 64-bit if it's doing nothing for you ATM.  That may or may not be the
case, however, provided of course you get the 64-bit side setup correctly
and optimized for your usage.

There's no doubting that 64-bit is currently somewhat more complex, in
particular for those who need to run 32-bit stuff not yet available in
64-bit.  For that reason, it could be argued that staying with 32-bit for
the moment is a better choice.  However, 64-bit amd64 *IS* the successor
to 32-bit x86, that seems rather self-evident by this point.  It could be
argued that getting in on the 64-bit stuff now will not only give you a
head-start later, but a better understanding, as you /do/ still have to
deal with some additional complexity in the 32-bit/64-bit stuff, that will
be pretty much taken care of down the road.  Whether that better
understanding is valuable enough to you to justify the complexity
tradeoff or not only you can answer, BUT I believe it's critical that you
don't short-change yourself in making that decision by having a wrong
impression of just how powerful the 32-bit/64-bit dual-bitness of amd64
can be.

Realistically speaking, there's very little technical reason to run 32-bit
x86 where 64-bit amd64 (aka x86_64) is available.  It's all down to the
complexity of the solution.  The extra registers and the like available to
64-bit mode almost always more than make up for the additional length of
the address space, even where 32-bits of data is plenty for the
application being handled.

If you have significant reason to need 32-bit-only binary codecs (which
will almost certainly eventually be available in 64-bit as well, as even
MS is headed that direction), or run 32-bit only games, then yes, the
compound 32/64-bit solution is more complex.  However, even those should
run as good, and likely better, on a 64-bit base system, due to the
additional efficiencies in the 64-bit system.  There's nothing unavailable
on the 64-bit system that's available on 32-bit, because 32-bit can run on
both, provided the rules are followed, and the 64-bit system in general
should run more efficiently.

If you have no significant reason to run 32-bit only code, than
unquestionably, 64-bit is superior.  However, it does look like that's
going to be a way off, for your usage.  It should come, however, and one
of the questions you have to deal with is whether dealing with the
additional complexity and learning the system now, is worth the hassle,
over having to deal with somewhat less hassle later, given that the
technical side either comes out marginally in favor of amd64 or as a wash.

Basically, it comes down to this.  If you don't view yourself as a power
user, if you'd rather deal with a little less complexity later, than
somewhat more complexity now, and the loss of a marginal bit of
performance in the mean time doesn't significantly bother you, than
honestly, 32-bit is likely going to be the better choice at this time. 
If, however, you consider yourself a power user, if dealing with a bit of
additional technical complexity now as compared to if you wait sounds more
like an enjoyable challenge than drudgery and hassle, if you don't like
the idea of yielding even that marginal performance difference, then you
probably want to go with amd64 now, sooner rather than later.

Personally, I definitely consider myself in the latter category, and
deliberately chose to go amd64 a couple of years ago, in part /because/ I
wanted in on the "ground floor" of the architecture -- I didn't want to
miss out on all those challenges.  Many of them are already gone -- it's a
significantly smoother ride now than it was.  However, there's still
enough left that getting in now and learning how to deal with some of
those remaining issues will give you a better understanding of your
architecture than those who wait until they don't have to run 32-bit at
all, because everything is available in 64-bit.

There is, however, nothing at all wrong with being simply a user (altho
on Gentoo, being a Gentoo user by definition means being the sysadmin of
a Gentoo system as well, with the responsibilities that brings to keep
the system secure and the like), one who prefers a system that "just
works", who has other areas in their life they consider more important,
with all the complexity there they can manage, and thus, who has no
interest in additional complexity when it comes to their computer.  This
sort of user will probably want to stay 32-bit at this point, and
honestly, but for the fact that Gentoo has such a helpful community and
such highly regarded documentation, might be better off choosing another
distribution, as well.

Your reality is actually most likely somewhere in the middle, particularly
as  you've already rejected some of the other distributions, and there
must have been a reason for doing so, which by definition already
self-selected for a Gentoo bias to some extent.  However, it remains a
choice you have to make -- none of us can or should try to make it for
you, and while we certainly have our own biases and certainly do what we
can in the persuasive arena, I doubt any of us would /want/ to make your
decision for you.  =8^)

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman in
http://www.linuxdevcenter.com/pub/a/linux/2004/12/22/rms_interview.html


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