You are shopping for a new PC and the sales rep tells you “Model A has a dual co

Question

You are shopping for a new PC and the sales rep tells you “Model A has a dual core processor running at 1.5GHz and Model B has a quad core processor running at 2GHz.” Based on this info which statement(s) are you sure are true?

a) Model A with the quad core processor will be at least twice as fast as Model B with the dual core.

b) Model B will use more power that Model A and increase your electricity bill.

c) Model B has a shorter clock cycle time than Model A.

d) Model B will execute 4 instructions in every clock and Model A will only execute 2.

e) None of the above

Explanation / Answer

a) No

Double the Cores Is Not Double the Speed

So let’s say you have the right software and all your other hardware is the same. Would a quad-core processor then be twice as fast as a dual-core processor? Nope.

Increasing cores does not address the software problem of scaling. Scaling to cores is the theoretical ability of any software to assign the right tasks to the right cores, so each core is computing at its optimal speed. That’s not what happens in reality.

In reality, tasks are split sequentially (which most multi-threaded software does) or randomly. For example, let’s say you need to accomplish three tasks to finish an action, and you have five actions like this. The software tells Core 1 to solve the first task of Action 1, while Core 2 solves the second, Core 3 the third; meanwhile, the idle Core 4 is told to solve the first task of Action 2.

If the third task is the hardest and longest, then it would have made sense for the software to split the third task between Cores 3 and 4. But that’s not what it does. Instead, even though Cores 1 and 2 will finish faster, the action will have to wait for Core 3 to finish its task, and then compute the results of Cores 1, 2, and 3 together.

All of this is a roundabout way of saying that software, as it stands today, isn’t optimized to take full advantage of multiple cores. And doubling the cores does not equal doubling the speeds.

b) yes

Power Consumption

More cores also lead to higher power consumption by the processor. When the processor is switched on, it supplies power to all the cores, not just one at a time.

Chip makers have been trying to reduce power consumption and make processors more energy efficient. But as a general rule of thumb, a quad-core processor will draw more power from your laptop (and thus make it run out of battery faster).

c) No

Clock Cycle is the speed of a computer processor, or CPU, is determined by the clock cycle, which is the amount of time between two pulses of an oscillator. Generally speaking, the higher number of pulses per second, the faster the computer processor will be able to process information

d) yes

Dual core - Its like having two brains so you can do two tasks at the same time. The same applies to quad core - 4 brains so 4 tasks at the same time.

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.