Hey all.

I just recently got a deal on a MB/CPU combo which has an Intel Pentium-D 805 processor. I know this is probably too "old hat" to a lot of you to be spending any money on, but it is still noticably faster than my Athlon XP 2600+ that it replaced.

Anyways, this is my first dual-core/SMP system I've ever had, so I've just got a few questions. I'm running Ubuntu Linux with the proper "686" SMP kernel, and `cat /proc/cpuinfo` indicates that two CPUs are being recognized.

1. The Pentium-D 805 CPU is essentially two identical "Pentium 4 with HyperThreading" cores on the same chip, correct?

2. The front of the CPU packaging (the box) mentions "Intel EM64T supporting 64-bit computing". This is a 32-bit processor, so what does this statement mean?

3. How, in general, does Linux and/or the hardware delegate what core does what in just a normal, desktop setting (i.e. running a graphical desktop with several, non-threaded applications running)? Does any given process "commit" to one core or the other, or does the processing load for each process get passed between the cores?

4. Is it possible to force a process to use one core or the other? For example, if I wanted to compile a kernel whilst still running other applications such as OpenOffice.Org and Firefox, could I have the kernel compile while using 100% of "core 0" and then have everything else run on "core 1"? This seems like it could offer some obvious usability advantages in such scenarios--namely, the desktop applications ought to run at close-to "full speed", correct?

Thanks!

Yes but I believe that the hyperthreading is disabled when you look at the cpuinfo is there an HT there or even a setting in the BIOS to turn it on because if there was you would see four cores in the cpuinfo if enabled.
That means you have a 64bit not 32bit cpu.
Gets passed between the cores with load balancing if the task is multi-threaded then it gets run on both cores.
You can do that anyways there is no reason to not be able to run many tasks at once unless the intel processors are real dogs. On my AMD X2 I can encode a video, listen to music, download, surf the web and have many other widows open doing other things and not even notice any slowdown. You can if you want check into the schedutils package (this name on Debian might be different for your distro) which allows you to set the cpu affinity if you want/need too.

Actually it is better not to force this manually, that's because the schemes used to schedule tasks over the cores do a way better job then you do . In fact your processor does a lot of waiting on IO, in general. If you use OO.org or firefox your Pentium D will typically use between 2-5% processor time (of one core). Because of this it's probable that it takes longer to compile your kernel if it's compiled on a single core than if you let Linux do the scheduling.

the processor supports EM64T, so it is really a 64-bit processor. Pentium D processors are not hyperthreaded. only pentium extreme edition

And while you're at it, go to:
http://www.tomshardware.com/2006/05/..._41_ghz_cores/
so your processor is not too "old hat"

Thanks for the responses!

So it really is 64-bit, eh? Since I installed this board/processor in a pre-existing machine running a 32-bit CPU (and, thus, a 32-bit install of Ubuntu), do I stand to gain any performance by reinstalling my OS with a 64-bit distro of Linux?

Thanks for the link, onedingo. I did hear about the overclockability of this CPU and might OC one day. However, with this ECS motherboard, I'm not going to overclock this thing by 1 MHz .

yes, you will see some benefit, but getting an smp kernel will give more, because it will enable use of both cores