For a long time, single core performance has been the most important feature for gaming. Though we are getting better multi-threaded games, we are still pushing for the maximum single core performance instead of cores. Why can’t 16* 2ghz cores do roughly as good job as 8* 4ghz (of the same CPU architecture), especially in gaming?
They say that software programmers have to manually split the jobs for multiple cores. Why? Why does the OS even need to operate multiple cores in the first place? To me this sounds like bad workplace management, where the results depend on pushing the limits of the same few people (cores) instead of splitting the work. I feel like making just a big bunch of cheap cores would give better performance for the money than doing tons of research for the best possible elite cores. This works for encoding jobs but not for snappy game performance.
Now, one limitation that comes to mind is sequential jobs. Things where the steps need to be done in a certain order, depending on the results of the previous step. In this case, higher clock speed has an advantage and you wouldn’t even be able to utilize multiple cores. However, I still feel like the clock speeds like 4 000 000 000 cycles per second can’t be the limiting factor for running a game over 150 frames per second. Or is it? Are the CPU jobs in game programming just so sequential? Is there any way to increase the speed of simple sequential jobs with the help of more cores?
Bonus question: How do multiple instructions per cycle work if a job is sequential?
Bonus question 2: GPUs have tons of low power cores. Why is this okay? Is it just because the job of rendering is not sequential at all?
In: Engineering
It’s hard to convey to someone just how difficult multi-core programming is if they don’t have a strong programming background.
> instead of splitting the work
And therein lies the rub: splitting work across cores is extremely difficult. Without programmer assistance the CPU cannot meaningfully understand the program structure to extract significant work.
> Are the CPU jobs in game programming just so sequential?
To put it simply, yes. Working across multiple cores is immensely difficult for the bulk of the work a game does.
> Is there any way to increase the speed of simple sequential jobs with the help of more cores?
This depends entirely on the specific details of the jobs.
> How do multiple instructions per cycle work if a job is sequential?
Each individual instruction engages different parts of the CPU at different times. So you can have to instructions “executing” simultaneously so long as they are using different parts of the CPU.
> GPUs have tons of low power cores. Why is this okay? Is it just because the job of rendering is not sequential at all?
Correct. Graphics rendering is a whole lot of “do this operation on every pixel” and each operation is independent of all others. You can have a thousand running simultaneously without much work by the programmer.
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