Intel Architecture Confusion

[Isidore Nabi]

I recently bought an inexpensive server that came with dual 3.0 GHz Xeon processors. Based on what little I knew, I assumed this meant I'd be getting two 64-bit processors, but when I went to install Fedora 10, the installer said I had the wrong architecture and that I needed to use an installer for an i686 architecture.

I don't suppose the installer could be wrong about that, but I don't know of any way to verify it. The hardware information in the BIOS setup utility only shows the speed (3.06 GHz), manufacturer ("GenuineIntel"), type ("Intel® Xeon™"), CPUID ("F029") and L2 cache (512K). Nothing about the architecture.

So, bummer. My $380 server wasn't quite as good a deal as I thought it was. But I soldier on.

The next puzzler is that, when I go to download the i686 install CDs, there aren't any. There are only i386, x86_64 and ppc Install CDs, but there is a "Live CD" for i686. Hmmm. What can this mean, I wonder. Well, I think, since I'm installing this on a server, then "Fedora Desktop Live Media" doesn't sound like the thing for me. Besides, since there are i386 and x86_64 Install CDs, and x86_64 and i686 Live CDs, it kind of sounds like i686 and i386 are interchangeable.

Please don't judge. I'm not stupid, just not terribly knowledgeable about Intel architectures. I'm trying to figure this out, but there is a lot of incomplete, inaccurate, misleading information out there, so you can spend a lot of time going in circles.

So, anyway, I download the i386 install CDs and do my installation, and everything seems to go fine until I reboot and hit the snag with the RAID card not being recognized. This problem has nothing to do with the CPU architecture, but in researching that issue I keep running into the i386/i686 dichotomy and wondering if I did the right thing.

As I now understand it, the i686 is like a more advanced version of the i386, so if you install the i386 version, it will work, but you're not taking advantage of all the capabilities that were added to the i686 architecture. Is that about right?

I've also learned that, to get the i686 version, you have to either use the i686 Live CD or build it yourself, and if you want all your software to be the i686 versions (if available), and you want to be able to update and upgrade everything via yum, you can either install the i686 version from the Live CD or build everything yourself.

So now I'm thinking that the i686 Live CD is the way to go?

But I'm still puzzled about a couple of things:

1. Why is there no i386 Live CD and no i686 install CDs? It just makes it harder figure out which images to download.

2. How does Intel get away with marketing chips with completely different architectures under the name, "Xeon," without even giving buyers a clue as to what they're getting? I mean, they make a big deal about how many cores a chip has, and how fast it is. Don't they think we also care about 32-bit vs. 64-bit?

[Isidore Nabi]

Now that I have Fedora 10 (i686) up and running, I open up the System Monitor and it shows me that I have 3 processors.

WTF?????

[markkuk]

Originally Posted by Isidore Nabi

if you want all your software to be the i686 versions (if available), and you want to be able to update and upgrade everything via yum, you can either install the i686 version from the Live CD or build everything yourself.

There aren't i686 varsions of all packages even on the LiveCD. Only kernel, glibc and openssl packages come in i686 versions.

Originally Posted by Isidore Nabi

1. Why is there no i386 Live CD and no i686 install CDs? It just makes it harder figure out which images to download.

There isn't space to include multiple optional packages on the LiveCD (and the simplified installer probably couldn't handle them anyway). The i386 install media has i386/i586/i686 versions of the most important packages and the right ones are picked at install time.

[manuleka]

Originally Posted by Isidore Nabi

I recently bought an inexpensive server that came with dual 3.0 GHz Xeon processors. Based on what little I knew, I assumed this meant I'd be getting two 64-bit processors, but when I went to install Fedora 10, the installer said I had the wrong architecture and that I needed to use an installer for an i686 architecture.

I don't suppose the installer could be wrong about that, but I don't know of any way to verify it. The hardware information in the BIOS setup utility only shows the speed (3.06 GHz), manufacturer ("GenuineIntel"), type ("Intel® Xeon™"), CPUID ("F029") and L2 cache (512K). Nothing about the architecture.

So, bummer. My $380 server wasn't quite as good a deal as I thought it was. But I soldier on.

.........................

2. How does Intel get away with marketing chips with completely different architectures under the name, "Xeon," without even giving buyers a clue as to what they're getting? I mean, they make a big deal about how many cores a chip has, and how fast it is. Don't they think we also care about 32-bit vs. 64-bit?

would pay to do abit of research and a few queries before spending ~ $400
i think L2 caching would tell something about the sort of architecture too... (my guess)

[Isidore Nabi]

Originally Posted by markkuk

There aren't i686 varsions of all packages even on the LiveCD. Only kernel, glibc and openssl packages come in i686 versions.

So I noticed as I installed all the packages I wanted with Add/Remove yesterday.

Originally Posted by markkuk

There isn't space to include multiple optional packages on the LiveCD (and the simplified installer probably couldn't handle them anyway). The i386 install media has i386/i586/i686 versions of the most important packages and the right ones are picked at install time.

So you're saying the i386 distribution would have installed the i686 kernel and those other packages anyway? Damn. I wasted a whole day.

[Isidore Nabi]

Originally Posted by manuleka

would pay to do abit of research and a few queries before spending ~ $400
i think L2 caching would tell something about the sort of architecture too... (my guess)

At the time I didn't know I needed to do the research. I thought Xeon=64-bit. Ask around and you'll find most people think so. Some people I've talked to have been incredulous that a 3 GHz Xeon could be 32-bit. They thought the 32-bit Xeons were phased out before the clock speeds got that high.

So the lesson here is that if they don't say it's 64-bit, it probably isn't. You can't infer anything from the clock speed. Maybe you could from the L2 cache, but I wasn't aware of what it was until I got it.

It's still not a bad server for the money. It has 4 hot-swappable 250GB SATA drives and a RAID card. The thing that worries me most right now is that after about one out of every three restarts the hardware monitor shows only three CPUs. I have no idea what that's about.

[marko]

Some ideas for confirming the number of cores seen and information about them:

1) You can get lots of details about the cpus on the system by installing 'x86info' and running that as root:

su
<root password>
yum install x86info
x86info

2) look in the /proc/cpuinfo file, it has a separate section headed with
processor : #

where the # is the id number of each core ranging from 0 to N-1

3) run the 'top' command and press the '1' key to activate the per cpu feature. In that mode, top will shows each cpu's stats.

[Isidore Nabi]

Originally Posted by marko

Some ideas for confirming the number of cores seen and information about them:

1) You can get lots of details about the cpus on the system by installing 'x86info' and running that as root:

su
<root password>
yum install x86info
x86info

Hey, that's great! Thank you!

Here's what I get:

Found 4 CPUs
--------------------------------------------------------------------------
CPU #1
/dev/cpu/0/cpuid: No such file or directory

Then there's a lot of very detailed information about each processor, and then this:

WARNING: Detected SMP, but unable to access cpuid driver.
Used Uniprocessor CPU routines. Results inaccurate.

Any idea what that's about, and could it be related to the intermittently missing processor issue? I was able to get the CPUID from the BIOS setup utility earlier.

Originally Posted by marko

2) look in the /proc/cpuinfo file, it has a separate section headed with
processor : #

where the # is the id number of each core ranging from 0 to N-1

That looks like the same information I got from x86info.

Originally Posted by marko

3) run the 'top' command and press the '1' key to activate the per cpu feature. In that mode, top will shows each cpu's stats.

This is all very interesting. All I need to do is compare these results with what I get the next time I catch it reporting only three processors. It might help me figure out which one is going missing.

In the BIOS setup utility you can see the operating temperature of each CPU and the speed of its cooling fan. Is there any way to access that information from the OS?

Thanks for the tips!

[marko]

Try installing cpuid package

yum install cpuid

and run cpuid

that will give a lot of info too

[Isidore Nabi]

Originally Posted by marko

Try installing cpuid package


and run cpuid

that will give a lot of info too

Yes. A lot more detailed information on the chip.