RFC: Optimizing for 386 (Part 2)

[Paul A. Houle]

On Fri, 25 Mar 2005 09:34:08 -0600, Derek Moore <derek.p.moore at gmail.com>  
wrote:

>
>> of RAM, but only ask for a paltry 80GB 7200 disk?  Either you have no
>> clue what you're doing, or you're trying to scam people into buying your
>> new gaming box for you.  Either way, I certainly hope nobody gives you
>> any money for that thing.  *snicker*

	People who grew up using PC's usually think SCSI disks are a big waste
of money.  My experience is that they're 2-3x faster for doing compiles.   
If I had a little
money to spend on building a compile system,  I'd seriously consider  
getting a few
9GB SCSI drives off ebay and using them for a temp directory to do  
compiles on.

>
> He's not the only one that believes compiler optimizations have an
> effect at runtime (if he was, Gentoo wouldn't exist).

      People who've tested it have observed that Gentoo is slower than most  
Linux distributions,  in particular,  Red Hat.

> Now that he's done the hard part of rebuilding the distro, and is
> providing it to everyone at his cost, hopefully users of his packages
> will submit quantitative and qualitative benchmarks of their favorite
> components.
>

	I'd really like to see what difference the Intel compiler makes.

	Another interesting question is what to do on AMD64.  We know that some  
things run faster in 32-bvbit mode and others run faster in 64-bit mode.   
(RAM use is different too,  which has knock-on effects on performance.)

	Solaris (both for SPARC and x86) ships with a 32-bit userspace and both  
32-bit and 64-bit kernels;  this has the nice effect that you can install  
Solaris 10 on any x86 box with one set of disks.  I think this is a good  
decision for SPARC (Debian does this for SPARC) but it's probably not so  
good on x86,  which benefits from the extra registers in x86-64.

	Still,  there might be some people who'd like an x86-64 kernel with a  
32-bit userspace (it would work like a Xeon box with PAE;  a good setup  
for a mod_perl web server with >4G of RAM.)  For top performance,  one  
could imagine shipping a 32-bit or 64-bit binary depending on what's  
fastest for a particular app.