P4 HT

[Brian Kelsay]

Greg Kedrovsky wrote:

> This is just a curiosity post. Has anyone had any experience with Linux
> with a P4 HT processor? Is the thing pretty much the same as a "regular"
> P4?
> 
> I have a old P3 running on what I think is a 100MHz board, and tried to
> do some video capture from a DV camera (kid's 5th birthday). The capture
> was crappy - dropped a bunch of frames and left the video choppy. So, I
> read through the sys reqs and figured now would be a good time to
> upgrade.
> 
> I went shopping today and ran into the P4 "HT." The salesman (working on
> commission, of course) really talked it up and said it was the one for
> me. The way he explained it made it sound like the processor worked
> differently than other (older) P4s - something about the older P4s using
> half the processor for "check sums" or something like that, and the
> other half for actual processing. This P4 HT, then said he, used all of
> the processor for processing, yadda yadda yadda... 
> 
> Pricey, too. $267.00 (US), just for the P4 (no motherboard, RAM or
> donuts included). 
> 
> So, I'm kinda curious, and therefore will undoubtedly read a little about
> the HT. But, I thought I'd post to see if anyone is running one of these
> things with Linux. Does it work okay?

HT, meaning Hyper Threading.  Under Windows and Linux it can appear as 2 
processors at boot and in some cases actually run like a dual processor 
machine.  I think what they do is by having a wider data path from the 
ram to the CPU and to the mobo you can make calculations 2x per clock 
cycle, each time refilling the cache and with branch prediction, doing 
something like a read-ahead on a HDD, actually do calculations ahead 
based on what the system expects you will need in the near future.  This 
is all very complicated of course and I doubt I have cleared it up.  Go 
to Tom's Hardware, AnandTech, or ArsTechnica or all three to look for 
fine articles on the P4 HT technology.  AMD has a similar technology, of 
  course in their new processors also.  It all has to do with the DDR 
ram and the fat pipes between the CPU, ram and mobo.  This is all 300MHz 
FSB and nd up, maybe 266 up, can't remember.  It's just like adding 
another lane to 435.  All of a sudden you can move more cars in the same 
amount of time.

Not only will the processor be more expensive, but the ram and mobo are 
too, of course, and ram just went up for DDR.  When you told the 
salesman you were working w/ video processing, he steered you right to 
what you needed, possibly.  After research, you may find that you can 
get more bang for your buck out of an AMD chip with a similar FSB of 
400MHz and DDR 2xxx ram.  Definitely research this before you drop this 
kind of cash, unless it's just pouring out of you, in which case I'll 
help you take a load off.   Your best bet is to find a reputable online 
shop that lets you pick the motherboard, processor and ram  and will a 
least burn-in test this much ahead of time for you.  Even if you don't 
get the case and drives from them, some will do this.  I could probably 
send a few sites your way if you want or after I move, I could build you 
a custom system.  In any case, don't get what you don't need and don't 
waste your money.

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Somewhere there is a village missing an idiot.