When Intel and AMD launch new processors, they compare the performance of the new generation processors with the previous one. Among single & multicore performance improvements, they also put a spotlight on the IPC performance improvement.
But what exactly is the IPC of a CPU & why CPU manufacturers are highly focused on it?
You should know about this because it plays a major role in boosting a CPU’s performance. And this article is all about explaining the IPC.
So, without any delay, start wondering.
What is a CPU IPC & How Does it Work?
IPC or Instruction Per Clock is actually a metric that counts or measures the number of works a processor completes in each clocking time. That means the number of instructions a processor executes at a certain clock. That determines how one core performs based on the CPU frequency.
The more improved IPC means the better the CPU is. That’s why two different generation processors might have the same clock speed, but there is a huge difference in performance.
Modern-gen processors are so much faster, even though they share the same single-core clock speed as the older ones.
So, what’s the catch here, and how two different processors with the same clock speed & core can outrun one another?
The magic lies in the CPU micro-architectures and how those instructions are executed.
Suppose, two persons were instructed to arrange 100 books on a shelf, and both have the same working speed. Even with the same speed, one person finished arranging those books within 15 minutes, whereas another one finished it in 10 minutes. So, how’s that possible?
The trick is, the winner knows better how to arrange those books in a faster way. Similarly, two different processors with the same 3.2 GHz clock speed per core can outrun one another because of the higher IPC.
Among these two, the CPU which has a better-optimized data execution algorithm & balanced architecture will execute all the instructions faster.
IPC Working Procedures
A CPU’s IPC works like a mechanism that helps two cores to communicate with each other. IPC handles the data sharing between cores and gives coordinates to achieve any task faster. That’s why a processor, with better IPC, can handle all the work between the cores more effectively.
IPC can be designed in many ways, but the most common structure is the shared memory segment among the threads. Don’t get confused! Let me explain.
When the CPU executes any instruction, it needs data. That’s why the first core requests the data from the shared memory, and the second core collects that data from the shared memory. Then, it passes that data to the first core.
How CPU’s IPC is Calculated
IPC calculation is achieved by running several codes, calculating the required number of machine-level instructions, and high-performance timers to count the required number of clock cycles to complete it on the main hardware.
To simplify, divide the number of instructions executed by the number of the clock cycle within a specific time period. So, the IPC calculation formula is as follows:
IPC = Number of instructions executed / Number of clock cycles.
However, the CPU performance counters count the number of instructions that are executed, and the CPU clock frequency obtains the number of clock cycles.
So, what’s the main goal of this IPC calculation?
Well, from this, you can determine the executing instructions efficiency of a CPU. Hence, the digit of executed instruction per clock cycle isn’t consistent for a given processor.
If you compare different IPC instruction sets, you’ll notice that even with a simpler instruction set, it is possible to achieve a higher IPC than a complex one.
Is IPC More Important than Speed?
Speed does matter if you compare two CPUs with the same architecture, but speed won’t be a factor when you are comparing two CPUs with different architectures. If you look at the recently launched AMD Ryzen Zen3 processors, it gained almost 19% uplift for better IPC than its previous Zen 2.
Zen 2 came up with a 12 nm architecture, whereas Zen 3 changed the game by landing the processor market with a 7 nm. Well, there are major factors for IPC uplift, which are as follows:
- Better cache prefetching
- Execution engine
- Brunch prediction
- Micro-op Cache
- Front end
AMD’s Zen 3-based Ryzen 5-5600X processor outperforms Zen 2-based Ryzen 5-3600X with its higher IPC when all six cores are locked at 4 GHz. That’s why IPC is a fact over clock speed.
Moreover, the CPU’s architecture is also a fact in delivering higher performance. That’s why architecture is important, and it’s changing constantly. By any means, if you are curious to know your current CPU’s architecture, you can know that through some methods.
Which CPUs Have Higher IPC?
Recently, Intel launched its 13th gen Raptor Lake, which outperforms AMD’s 7000 series by a massive margin. Along with core count, Intel also uplifts the IPC, that’s where Intel flips the coin and changes the game against AMD. So, IPC improvement makes Intel the king again.
Before launching the i9-13900K, AMD’s Ryzen R9 7950X was the king of ultimate performance by surpassing every other same-level processor. But don’t misjudge the 7950X, it lost to 13900K after a head-to-head battle.
Both these processors have higher clock speeds & IPC. These processors can deliver top-level performance while gaming. After these two, intel’s 12th gen core i9-12900K has a higher IPC too.
Now, let me show you the benchmark of the IPC test of these three mentioned processors.
Here is the benchmark of IPC test between i9-13900k, Ryzen R9 7950X, and i9-12990k in a graph:
So, from this IPC benchmark test with Cinebench, you can clearly see which one has the higher IPC.
Pros & Cons of Using CPUs IPC
IPC is important for measuring CPU performance because it measures the time taken for two different methods to communicate with each other on the same processor. The technique for communicating with each other is more responsive for a CPU with a higher IPC.
As you know, IPC can measure the number of work done by the process in a CPU. Plus, it helps with instruction optimization and bottleneck detection. But it has both merits & demerits. Let’s get into the pros of IPC first.
Below are a few pros of using CPU IPC:
- IPC optimizes coding performance.
- A CPU with a higher IPC minimizes the load on the system.
- Along with speed, it provides stability for applications.
So, these are the few positive sides of IPC, but nothing comes with perfection. That’s why using IPC comes with some demerits. Why not put a light on that too?
The followings are some cons or drawbacks of using CPU IPC:
- IPC can sometimes slow down the entire performance.
- Without improper implementation, IPC may lead to code vulnerabilities.
- Developing custom code libraries to utilize IPC takes time and lots of money.
- IPC may cause communication problems between threads and trigger instability.
- It’s difficult to debug IPC’s bugs.
So, these are the pros & cons of using IPC on CPUs. I hope you got all the points clearly.
Remember, higher IPC will improve a CPU’s performance for sure. But you have to count the clock speed too because GHz is a matter in terms of delivering higher performance.
Apart from everything, IPC is not the only factor that determines a processor’s horsepower, core count is vital in a meaningful way.
How to calculate my CPU IPC?
To calculate your CPU’s IPC, you must divide the number of instructions executed by the number of the clock cycle within a specific time period.
How to calculate CPU times using IPC?
You can calculate CPU times using IPC with a simple formula, and that is, CPU Time = IC * CPI / Clock Rate. Here, IC = Instruction Count of a Program, CPI = Cycles Per Instruction.
Does Higher GHz mean a faster CPU?
A CPU with higher GHz is faster, and it’s true when you’re comparing the same brands and the same generation’s CPUs.
IPC or Instructions per clock is crucial when you want the best performance from a processor. In this article, I have explained all the significant facts about CPU’s IPC, including their working procedures and why it is sometimes crucial over the CPU’s clock speed.
Therefore, now you have a clearer understanding of IPC. If you need more info, ask me in the comment box below. Have fun learning new things!