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Old 2005-02-08, 13:48   #1
tha
 
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Default Gimps awaiting a major transition

L.S.,

The more I am reading about it, the more I am thinking about it, I've come to realize that the GIMPS project has to prepare itself for the new IBM, Sony, Toshiba Cell processor. There are nice new functionalities, opportunities and higher speeds awaiting us, but also threads that need to be considered and dealt with.

The Cell processor has 8 FPU's aboard, each of them capable of outrunning an Intel Pentium IV. Also, grid computing and networking is the basis for the design of the chip, very different from todays networks, where no processor is aware of other processors.

The current prime95 program is handoptimized for the CISC Pentium processor, and to some extend the Athlon. With the Cell processor being RISC based there will be less need to work with a handoptimized program. Hence people can much easier write their own LL test program and run it outside the GIMPS project. This could jeopardize the GIMPS rule that you would have to share the EFF prize. Most members joined even before there was a monetary award, and to prevent double work a server coodinating the hand out will still be welcome to everyone willing to test, but one could work ahead of the server range more easily.

I think the GIMPS project could benefit from cooperation with the chipdesigners if we would be able to write the fastest FFT implementation for the Cell processor. I would guess though that they are working on that themselves.

Also more competition from other projects can be expected when network oriented processors become available. Projects offering money for making your processor available for all kinds of commercial and scientific can be expected to pop up everywhere competing for resources.

The future for sure is interesting.
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Old 2005-02-08, 14:04   #2
jinydu
 
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I think you're referring to this:

http://story.news.yahoo.com/news?tmp...cell_processor

"Cell's designers say their chip, built from the start with the burgeoning world of rich media and broadband networks in mind, can deliver 10 times the performance of today's PC processors."

However, the article then goes on to cite seemingly contradictory figures:

"Cell appears to have an advantage in the number of transistors — 234 million compared with 125 million for today's latest Pentium 4 chips. Traditional chip makers, however, have regularly doubled their number of transistors every 12 to 18 months."

"Cell is said to run at clock speeds greater than 4 gigahertz, which would top the 3.8 GHz of Intel's current top-speed chip."

If Cell was 10 times faster, wouldn't we expect 1.25 billion transistors and 38 GHz?

Last fiddled with by jinydu on 2005-02-08 at 14:06
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Old 2005-02-08, 14:38   #3
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Quote:
Originally Posted by jinydu
"Cell is said to run at clock speeds greater than 4 gigahertz, which would top the 3.8 GHz of Intel's current top-speed chip."

If Cell was 10 times faster, wouldn't we expect 1.25 billion transistors and 38 GHz?
There are other, and perhaps more efficient ways, of utilizing millions of transistors than turning them into ridiculously long pipelines. John "Hannibal" Stokes of Ars Technica has written an excellent article about the essentials of CPU design on the background of Moore's Law. Highly recommended reading for hardware freaks.

regards, Leif.
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Old 2005-02-08, 16:17   #4
Jeff Gilchrist
 
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Speaking of Hannibal, he just posted his own article about the Cell processor here: http://arstechnica.com/articles/paedia/cpu/cell-1.ars

Part 2 coming soon.
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Old 2005-02-08, 16:59   #5
Paulie
 
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Quote:
Originally Posted by tha
L.S.,
The Cell processor has 8 FPU's aboard, each of them capable of outrunning an Intel Pentium IV. Also, grid computing and networking is the basis for the design of the chip, very different from todays networks, where no processor is aware of other processors.
Unfortunately Cell is geared to single precision SIMD. GIMPS needs double precision.
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Old 2005-02-08, 17:36   #6
R.D. Silverman
 
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Quote:
Originally Posted by leifbk
There are other, and perhaps more efficient ways, of utilizing millions of transistors than turning them into ridiculously long pipelines. John "Hannibal" Stokes of Ars Technica has written an excellent article about the essentials of CPU design on the background of Moore's Law. Highly recommended reading for hardware freaks.

regards, Leif.
Indeed. There are a number of improvements that would greatly benefit
the domain of computational number theory without increasing pipelines
and without adding a lot more gates:

(1) Much larger L_1 and L_2 caches and lower latency to main memory
(2) More gates devoted to integer multiplication and division. The Pent IV takes 37 cycles to do a division!
(3) A scatter/gather capability

etc.
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Old 2005-02-08, 20:18   #7
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The Intel P4 can do 8 single precision ops using SSE2, (using two SSE2 registers), so the cell processor isn't ahead of it, yet.

As paulie mentioned GIMPS needs double precision so it doesn't help.


Are there ways of using single precision math for GIMPS ?

If so are they practical/usable ?
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Old 2005-02-09, 02:57   #8
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Code:
the Cell processor being RISC based there will be less need to work with a handoptimized program.
Non-sequitor.

Anyways, the cell processors are all single-precision, and if they weren't, you couldn't run just one LL test on them. The processors are designed to work all independently. You can't share a FFT across them. You'd have to run independent LL tests on each.
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Old 2005-02-09, 03:33   #9
moo
 
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the program could be written to go in order shooting one after neother so 1234567812345678 that would introduce quite a lot of performance actualy 2-8 and keep 1 running the program
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Old 2005-02-09, 03:44   #10
marc
 
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Quote:
Originally Posted by ColdFury
You'd have to run independent LL tests on each.
Exactly. If your PC happens to have 8 cells in it then you can run 8 LL tests in the time you'd usually run 1. It just so happens that LL tests aren't suited to it but I doubt Sony/IBM/etc. had us in mind when they started the design.

If what the various articles are saying is true then our nice and cheap personal computers will have several of these in them and will also be able to call on any we have lying around in our PDAs, microwaves, playstation 3s and whatever other technical gizmos we have lying around. I'm sure a lot of people on these forums would love the ability to do 2 LL tests while the other 6 cells are crunching their Doom 4 or whatever other ways we can find to waste our CPU cycles.
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Old 2005-02-09, 05:15   #11
moo
 
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actually if it was able to do that i would sugest that you would run it in a line from like i susgested earlier but that would take a lot of code but since we cant due to the single point it doesnt really help us unless we find a way to use 2 of them togeather
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