Experience in optimizing game performance

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Introduction to Optimization

When it comes to game optimization, it is often divided into these steps in game development:

• First, we need to determine what problems often occur in the game - Profile

• Then determine in which direction to optimize performance - Analyze

• *** Then try to solve the problems one by one - Solve

In game development, you must first make tools, perform profiles, and then optimize. Therefore, when talking about optimization, you have to talk about profiles.

Some common tools come with the engine and IDE, such as Unity's built-in Profiler, which includes a variety of performance analysis tools such as CPU, GPU, Memory, etc. Others such as GPA, Xcode Instrument and Visual Studio, Intel's built-in memory management tools also need to be learned and used when necessary.

Other tools need to be written according to the needs of the game, such as turning off all special effects with one click, changing the resolution with one click, etc., setting the number of NPCs on the field with one click. Simple games such as Papa Three Kingdoms use shortcut keys to open the Profile function, and more complex games such as Uncharted use the in-game console to perform more detailed Profie.

Next, let’s talk about the four main considerations in game optimization:

CPU

Questions raised:

• Due to the large amount of calculation in a short period of time, the smoothness of the picture is reduced, commonly known as frame skipping

• Severe fever and high power consumption

Common optimization methods:

• Divide the calculation into multiple logical frames to avoid performance overload in a short period of time, commonly known as "time-slicing".

• Cache as much cacheable data as possible to avoid repeated calculations and repeated memory allocation. A common example is the "memory pool".

• Use reasonable algorithms and data structures, such as bubble sort and direct insertion sort, which are much more efficient than quick sort when the overall array is relatively ordered. Replacing quick sort with is a common idea for optimizing program sorting efficiency.

GPU

Questions raised:

• Severe fever and high power consumption

• FPS reduction

Common optimization methods:

• Optimize art resources, such as reasonably planning the atlas, agreeing on the maximum number of triangles of the model, and formulating reasonable particle effect specifications. This can be said to be the most important one in game optimization. Therefore, technical art plays a huge role in game development.

• Simplify or optimize shaders, such as compiling and loading shaders before the game starts.

• Use Batching to minimize DrawCall

• Use the compression format recommended by the platform, such as ETC1 for Android and PVRTC for iOS

IO and Network

Questions raised:

• Network delays or even disconnections

• Frame skipping caused by loading resources

• Loading time is too long

Common optimization methods:

• Use independent threads for loading. Some engines, such as Unity, can also use coroutines.

• Reduce redundant data in network packets

• Merge small packets to reduce the number of data requests

• Process the returned packets by framing

• Limit the frequency of sending packets within a certain period of time

Memory

Questions raised:

• Crashes and freezes, for example, Android's Low Memory Killer will kill programs that occupy too much memory when memory is low.

Common optimization methods:

• Dynamically load and unload resources. For example, when in the game, we can unload some UI atlases outside the game.

• Reducing resource quality or screen resolution is lossy optimization and is generally used as a means of ***

Some thoughts on the projects I have done

Need to focus on non-functional requirements

This thought came to me from the answer to the question "Why do many seemingly uncomplicated websites, such as Facebook, require a large number of *** experts to develop?" As the answerer said:

"In fact, from my experience, in general, for many software projects and products, the cost, difficulty and workload of non-functional requirements exceed those of functional requirements. In specific software fields, such as websites (especially websites with massive user scale such as Taobao and Facebook), finance (banking and securities), and telecommunications, the importance, workload and technical difficulty of implementing non-functional requirements are far greater than the implementation of functional requirements. Moreover, the implementation of functional requirements, in most cases, relies more on business experts (or good product managers) rather than technical experts, and the implementation of non-functional requirements is precisely an important issue that challenges technical experts."

After working on the game front-end for a while, everyone is complaining that the game front-end has low technical content and can only write business logic. However, the trap is that as a front-end developer, you should write as little business logic as possible. Have you paid attention to the following modules?

• Performance: Have you profiled your game to see if the above parameters meet the targets?

• Security: Can the release version of your game's front-end code still be easily decompiled by others? Can your game still be easily intercepted by players or have its memory data modified?

• Testability: Can your front-end code be unit tested? Can you fix all the bugs in the Model layer before QA testing?

• Data-driven: Can you create better tools for artists and planners to liberate their productivity?

Need to be good at defining the scope and narrowing the problem area

In the past few months, I participated in the development of two Unity3D projects, All People Assault and Honkai Academy 2, and encountered some issues related to performance optimization. When problems occur in the program, we often solve the problems through so-called "experience". This Quick Link capability is naturally very important, but experience is not the only thing.

But on the other hand, when we cannot find the answer from our past experience, we have to solve the problem by dividing the scope and narrowing the problem range. Many people tend to just stick to a partial vision in their own experience to deal with the problem, and the result will definitely not be satisfactory.

Summarize

In fact, the optimization of these four aspects always checks and balances each other. If you optimize one aspect well, problems in another aspect will arise. For example, if we use dynamic loading and unloading of resources, although this reduces memory usage, it will cause the problem of prolonged loading time on IO.

Therefore, when we optimize games, we should not pursue perfection too much. Good Enough Is Fine. We should finally achieve a balance among the above four aspects. We should avoid over-optimizing one aspect, which will cause problems in other aspects. Sometimes, it is better not to optimize at all.