Single P4 3.0ghz showing up as dual proc

[GrigLars]

I have an odd issue, but it doesn't seem to be hindering my Linux box.

I just built a new box last night, usuing an Intel 865PERL single processor board, and a 3.0 ghz P4 cpu with 1GB DDR400 RAM. The board and chip have 800mhz fsb and support "hyperthreading" (whatever that is).

Well, before I set it up, I put in Knoppix (Debian-based LiveCD) CD to test the hardware, and noticed it booted as a dual-proc (smp). Huh. I didn't pay too much attention to this until I installed Fedora Core 1, and noticed it default booted to an smp kernel. It runs great on smp so far, but there's only a single processor in the box.

Any clues as to what Linux is seeing? Will leaving it as smp screw up anything down the road?

[SuperNu]

Linux sees all P4 processors with hyperthreading as dual processors. It is fine. Hyperthreading is a way to speed up execution. The processor appears to be a dual processor, but in fact is a single processor. Some reviews have seen a 20%-30% performance increase due to hyperthreading. Here is a link from Intel which explains what hyperthreading is.

--SN

[Jman]

I'm quite skeptical of claims you can get a huge performance boost out of a CPU by letting software pretend it is two. I haven't tried it yet, but I don't think I would notice the difference.

Interesting to note that the Linux kernel was just as quick to support hyperthreading as Windows.

[SuperNu]

Hyperthreading isn't pretending to be 2 cpu's via software. From my hyperthreading link, Hyper-Threading Technology enables multi-threaded software applications to execute threads in parallel. This will allow multi-threaded applications to execute much faster. In order to get the benefits of hyperthreading under Linux, you have to use a smp kernel.

--SN

[sigusr]

My take on hyperthreading is it is an attempt to deliver data from from a slow process (800 mhz memory) using more than one pipe to a fast process (3 ghz processor). Just my .02 cents worth.