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CPU build for Linux ?

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July 14, 2004 5:38:28 PM

In a heated discussion with a Linux group, I was told
that the Opteron 64 from AMD was designed for the Linux Kernel, not for the NT kernel, hence better performance using
Linux. I ran across some speed tests done on http://www.yoper.com a NZ Linux group, and found a comparison chart for 22 distributions,notably Suse, Mandrake and the like. There seemed to be wild speed variations among
the different Linux kernels. Can any one help me on validating the statement about Opteron Architecture ?
appreciated-

More about : cpu build linux

July 14, 2004 7:20:29 PM

Humm...

I really do not think AMD designed Opteron for LINUX only. In fact, they designed AMD64 (Opteron, Athlon 64 and Athlon FX supports it) to enable 64bit computing in the x86 architecture.

They have done this, because Intel had their own 64bit architecture that is not x86 compatible (Itanium processors). So, AMD launched these 64bit LOW-COST CPU into the market and the Linux community are the early adopter of this technology. This may be the reason you think that AMD64 was designed for Linux, but it wasn't. It was designed to fight against Xeon and Itanium Intel processor, by offering a very good cost/performance/features.

Microsoft will launch Windows XP 64bit edition around the end of this year.

By the way, the difference in performance from different Linux Distro, is probably due to different Kernel version and/or 32 or 64 bit mode. Do you have shortcuts to these reviews or charts? If you can spot numbers or things that you don't understand or bugs you! Provide us shortcuts, we might help you or learn by reading those articles/reviews.

--
It's tricky to use words like <b><font color=green>AMD</font color=green></b> or <b><font color=blue>Intel</font color=blue></b> in a signature some users could think your are biased.
July 14, 2004 11:53:24 PM

Linux has native 64bit support for the newer amd processors, so in some cases it will perform better (and in some cases significantly better) than a similar application will in nt. However, unless you are making a server that will require a pretty massive ammount of computational power you're probally wasting the chip to put it in a linux machine. There are very few applications at this point that are pushing the high end of the computer envelope other than games, servers, and graphics design. All of which, except servers, you are probally better off to do in windows (Yes, i know gimp is quite good, but its not photoshop).

Presently, I'm building 2500+ systems for linux machines when required, they perform well and offer more power than any one of my customers has yet required.

<A HREF="http://www.lochel.com/THGC/html/shadus.html" target="_new">Shadus</A>
July 15, 2004 1:17:42 AM

I'm quite sure Opteron was designed with both Windows and Linux in mind. But really, the software is typically designed for the hardware, not the other way around.

Linux has an advantage over Windows in that it's (mostly) 64-bit clean already and is designed to port easily to other architectures. Linux ports have existed for Alpha, MIPS64, PPC64, SPARC64, etc. etc. for bloody ages now, so it only took a short hop to get AMD64-ready. That's about it.

As far as the extensive variance in AMD64-Linux benchmark scores...there's a lot of software that doesn't gain squat from 64-bit extensions and actually takes a performance hit from all the extra bits thrashing the cache.

So Linux on AMD64 has three memory models:

1) plain-jane x86-compatible 32-bit,
2) quasi-AMD64 mode (you get the extra GPRs but not the 64-bit addressing),
3) and full 64-bit mode.

Distros are still experimenting with the three models and trying to figure out what works best for which apps. There's an additional complication in that 32-bit and 64-bit libraries don't "just mix" on Linux--that requires a thunking layer, and thunking is one of those things that Linux developers just don't care for. So if you have a 64-bit app that requires some libraries, you'd better have 64-bit versions of all those libraries.

(Rumors I've heard, BTW, suggest that Jerry Sanders dragged MSFT onto the AMD64 bandwagon by using Linux as a bludgeon--threatening BillG with mile-high bar charts of projected AMD64-Linux adoption. Mind you, MS had already dipped its toes in IA64 but gained little traction and negligible ROI. So BillG was probably a little peeved at Intel as well.)

<i>"Intel's ICH6R SouthBridge, now featuring RAID -1"

"RAID-minus-one?"

"Yeah. You have two hard drives, neither of which can actually boot."</i>
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