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Compare having one ALU that is twice as fast as normal to having two ALUs

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May 25, 2010 3:41:53 AM

>Compare having one ALU that is twice as fast as normal to having two ALUs

hey i'm sorta stuck on an assignment :??:  so if anybody can give the answer in a simple way, it would b really greatl!

a c 81 à CPUs
May 25, 2010 4:24:49 AM

As per your specified scenario, the single ALU might get a work done in double quick time but the dual ALU's will get more work done in the same time frame.. Thus, for a single process, a single dedicated ALU environment will be better whereas in multiple process scenario the dual ALU setup is the most efficient..
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a b à CPUs
May 25, 2010 4:39:16 AM

Emperus said:
As per your specified scenario, the single ALU might get a work done in double quick time but the dual ALU's will get more work done in the same time frame.. Thus, for a single process, a single dedicated ALU environment will be better whereas in multiple process scenario the dual ALU setup is the most efficient..


Huh?

From a theoretical point of view, each would be able to do the same amount of work in the same amount of time. If the double speed ALU could do work on 1 item for 500ms, and the regular ALU could do 1 item for 1 second; then given 1 second, both units could complete 2 items.
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a c 81 à CPUs
May 25, 2010 4:50:00 AM

This is where the whole discussion comes down to the process design.. If the process is designed so that it can(or must) be executed in parts, then the dual ALU setup gets the advantage..
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a b à CPUs
May 25, 2010 4:58:55 AM

Emperus said:
This is where the whole discussion comes down to the process design.. If the process is designed so that it can(or must) be executed in parts, then the dual ALU setup gets the advantage..


If you do factor in the other parts of the processor, then dual-ALU wins. But the OP is just asking specifically about the ALU.
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a c 81 à CPUs
May 25, 2010 6:59:52 AM

Am not at all factoring the other parts of a processor.. By process i mean the code or the workload designed to be processed.. Basically the concept of thread optimization.. If one has to just look from a single task (or thread) point of view, then having a faster processor definitely is more beneficial than multiple slower processors..
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a b à CPUs
May 25, 2010 10:18:33 AM

Emperus said:
Am not at all factoring the other parts of a processor.. By process i mean the code or the workload designed to be processed.. Basically the concept of thread optimization.. If one has to just look from a single task (or thread) point of view, then having a faster processor definitely is more beneficial than multiple slower processors..



Trouble is, the OP didn't put in any other detail.

This would be like comparing (for simplicity's sake) a single-core Core 2 @ 4.0GHz and a dual-core Core 2 @ 2.0GHz. Technically they are made the same, and as the op asked the only difference is number of execution units and clock speed.
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May 25, 2010 12:22:46 PM

sorry about the question....i was in a hurry so i only asked part of it.....here's the full question

2. Compare having one ALU that is twice as fast as normal to having 2 ALUs at the normal speed, in terms of performance, amount of hardware, and power. If any part of your answer depend on aspects of the software being run (e.g., available ILP), explain how.

i just want to know the difference in terms of performance, hardware and power

thanks for the answers :) 
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