1.) If each stage is 1 clock cycle, calculate the number of clock cycles to execute a code stream of 10 instructions in a non-pipelined (i.e. sequential) fashion?
2.) Repeat part 1, assuming the instructions are executed in a pipelined fashion.
Would this be the right formula to use in this case: T = I * CPI * C
I am still kind of lost in this, if anyone can help that would be great.
To calculate the number of clock cycles to execute a code stream of 10 instructions, let's consider both the non-pipelined and pipelined scenarios.
1.) Non-pipelined (sequential) execution:
In this case, each instruction is executed in a sequential fashion, and the next instruction can only start execution once the previous instruction has completed. Here, the formula you mentioned can be used to calculate the total time (T):
T = I * CPI * C
- I: Number of instructions in the code stream (10 instructions in this case)
- CPI: Cycles per instruction, which represents the average number of clock cycles required to execute one instruction (assume it is given as 1 in this case since each stage is 1 clock cycle)
- C: Clock frequency, which represents the number of clock cycles per second (also assume it is given as 1 in this case)
Using the formula, the calculation would be:
T = 10 * 1 * 1 = 10 clock cycles
Therefore, it would take 10 clock cycles to execute the code stream of 10 instructions in a non-pipelined fashion.
2.) Pipelined execution:
In a pipelined execution, the instructions are split into multiple stages (Fetch, Decode, Execute, Memory, Writeback) that can overlap in time. Each instruction goes through these stages, and multiple instructions can be in different stages simultaneously. The pipeline reduces the overall execution time.
To calculate the number of clock cycles required in a pipelined execution, we don't use the same formula as in the non-pipelined case. Instead, we need to consider the concept of pipeline stages and data hazards.
However, since the information provided doesn't specify the number of pipeline stages or whether there are any data hazards, it's not possible to provide an exact calculation without these details.
In general, if the code stream has no data hazards and the pipeline stages are perfectly utilized, the number of clock cycles required would typically be closer to the number of instructions (10 instructions in this case) rather than the total number of stages. But without more information, it's challenging to provide an accurate calculation.
I recommend reviewing the specific pipeline design and any associated hazards (e.g., data hazards, control hazards) to determine the exact number of clock cycles required to execute the code stream in a pipelined fashion.