3 replies to this topic

[Apprentice123]

A machine M1 performs with frequency f1 = 2GHz in 10s. What is the frequency of another machine, M2, to run the same program, with 90% cycles of M1 and 25% higher performance of M1

Any tips on how to find the frequency of M2 ?

[gregwarner]

If M1 operates at 2×10^9 cycles per second (in other words: 2GHz), and it executes the program in 10 seconds, that means the program was executed in 20×10^9 cycles. M2 executes the same program with 90% of the cycles, so:

20×10^9 × 0.90 = x cycles (I'll let you do the math here.) :)

We also know that M2 executes the program with 25% higher performance than M1, which means it takes 25% less time. So:

10 seconds - 25% = y seconds

Lastly, you know how many cycles M2 executed, and you know how many seconds it did it in, so the frequency is simply:

cycles / seconds

[Apprentice123]

gregwarner said:

If M1 operates at 2×10^9 cycles per second (in other words: 2GHz), and it executes the program in 10 seconds, that means the program was executed in 20×10^9 cycles. M2 executes the same program with 90% of the cycles, so:

20×10^9 × 0.90 = x cycles (I'll let you do the math here.) :)

We also know that M2 executes the program with 25% higher performance than M1, which means it takes 25% less time. So:

10 seconds - 25% = y seconds

Lastly, you know how many cycles M2 executed, and you know how many seconds it did it in, so the frequency is simply:

cycles / seconds

M2 execute in 7,75 seconds and f2 = 2,4GHz ?

[gregwarner]

Roughly correct. I actually got 2.32 GHz, so I would've rounded down.