How fast is each core in a dual-core processor?

My Macbook has a 2.4 GHz dual core processor. Because it has two separate cores, that means it can execute two functions at once, right?

So does that mean each core is approx. 1.2GHz each (for a combined 2.4 GHz) or are they actually 2.4 GHz each, and therefore is effectively running at 4.8 GHz?

Dual (and quad) core processors confuse me.

Solution 1:

Each core runs at 2.4 GHz.

Though that doesn't mean that your system is twice as fast as a 2.4 GHz single-core system. Parallelism has (in principle) at most a linear speedup but in reality it's often much slower (though still faster than a single core).

Solution 2:

Johannes above is correct when talking about the max frequency for each core in a multi-core procesor. The frequency rating relates to each core. So, a 2.4GHz multi-core processor typically runs each processor at the 2.4 GHz max frequency. There are two exceptions (one very common and one new):

• A processor's frequency can be dynamically scaled based upon the required performance and power draw to save power when power is not needed or to lower temperature (P-State).
• Also, recent processors have a "Turbo" feature where one core runs faster than rated when other cores are not being used (Turbo Boost).

Solution 3:

To be perfectly clear, having multiple cores does NOT speed up any one program unless it was specifically designed for multi-threading.

The effect of having multiple cores is:

Each thread runs at most as fast as your core clock speed. And, parallel processing allows an application to run more than one thread at once.

This means that at most, your processing power will be double, but not on any one thread.