I was told that the CPU Clock is like a doorbell that informs the CPU about an upcoming program instruction. Each time an instruction is finished by the CPU, the clock can be “rang” again.
I understand that the CPU needs to take some steps to process an instruction. When all of these steps are completed, is this known as one “CPU cycle” and the amount of cycles per second is the clock rate measured in hertz? So would a clock rate of 3 GHz actually mean that the CPU can perform 3 billion instructions per second?
I find the CPU cycles and the clock rate a little difficult to understand. Because I’ve assumed that one cycle equals one processed instruction so 1Hz = 1 instruction but I’ve also read online that one instruction doesn’t always take one cycle.
So what exactly is one CPU cycle then and how does this correspond to the clock rate?
In: Technology
Each instruction is kind of like an assembly line, running to the beat of a song. Each station on the assembly line has to get its work done in one beat. So you can have multiple things being worked on simultaneously. A CPU core is kind of like a factory, in that it can have multiple production lines, but you can also have multiple factories, which would be multiple cores.
How much work gets done per clock depends on the microarchitecture. This site has a table for how long each instruction takes(latency, measured in clock cycles), and how many can be started or finished per clock cycle(throughput, measured in instructions per clock cycle): https://uops.info/table.html
More info on that here: https://uops.info/background.html
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