Many small partners who pay attention to hardware, especially CPU, should have watched AMD's Ryzen™ 7 5800X3D test, is the game performance particularly eye-catching? And its only change is to increase the level three cache, and then look at the history of CPU development, as if the change of cache has been a very important development, what are they useful? Judging from the performance of the 5800X3D, are they bigger and better?
Cpu's cache use is easy to understand, they are the same as memory, is to remember some data that needs to be called at any time, if the memory is the scratch paper when calculating, the cache is a bit like its own brain, the recorded things may not be much, but it is definitely fast enough to call.
Also like the process of doing math problems, the CPU cache is divided into several levels, and each core of the CPU has a small storage unit, that is, a L1 cache , which can be used to save some instructions in addition to temporary computing data. It can be seen as the most basic data of our brain calculations, such as 1+1, 2+2 of mental arithmetic, and whether the next step should be multiplyed and divided or added and subtracted.
The L2 cache is also available for each core, mainly storing the temporary data needed by each core, because the capacity is large, so it can only be placed next to the core. The data stored here is probably equivalent to a relatively large mental arithmetic data, such as 100×100, although it is also very simple and more frequently called, but the data is really large, and it is not as frequently called as the most basic calculation, so it has to be stored with a larger, slightly farther away from the core capacity.
L3 caches appeared slightly later, mainly because of the need for a place to store common data after the advent of multi-core processors, making it easier for different cores to call common data or exchange data with each other. If you want to use the brain metaphor, it is probably the scene in the brain when doing the application problem, and the common storage and interaction area with formulas, charts and other data. Of course, the speed is much slower than the first and second levels, and the capacity also needs to be larger.
In this way, the three-level cache is actually more closely related to memory and easy to understand, after all, these data are really complex and huge, and when stored in the brain, they are mostly used as a "backup" of scratch paper, and they have to be written down.
Then, understanding the usefulness of caching, their significance and impact on the CPU is easy to explain. For example, the first-level cache is integrated into the CPU architecture, and the unified architecture is the same under the Core i9, Ryzen 9 down to the Pentium Celeron, and the Velociraptor, which determines the computational efficiency of the processor core. L2 cache is now basically bound to the core, and the total amount of L2 cache per CPU depends only on how many cores there are, and the L2 cache capacity of each core remains unchanged.
So, what can be added or subtracted at will is the remaining three-level cache, what impact will it bring? This is related to the design idea of the CPU. In Core processors, the main functions of L3 cache are similar to those we mentioned earlier, but newer Ryzen processors are different because of the design of I/O chips and computing core separation, which has a large delay in communication with memory.
At this time, the significance of the three-level cache is more obvious, especially when there are many high-speed, scattered data storage, yes, here is the game, most of the office, daily, video and audio applications of data storage can of course also benefit, but in addition to some data calculations, the data storage mode is relatively flat, so the impact is not so big. That's why the Ryzen™ 7 5800X3D's gaming prowess has soared, while other tests don't seem to have improved much.
Of course, the upcoming CPU will also upgrade the L2 cache to provide more powerful computing power, such as the 13th generation Core's performance core L2 cache increased to 2MB, the Ryzen™s 7000 per core headphone cache increased to 1MB, and so on. However, some small partners will probably be a little strange, why not simply increase the cache, can not improve more performance? This is not necessarily the case, in addition to the cache is too large may produce a decrease in access efficiency, they also have a great impact on the complexity of the chip.
It is particularly obvious from the relatively independent three-level cache, which often occupies an area larger than the computing core, which will definitely increase power consumption, heat generation, affect the frequency, and the number of cores, so the new architecture CPU has not continued to improve the three-level cache. However, AMD also said that zen4 will also have ultra-high cache models, which seems to be a good way to upgrade the version, and should also wait for the process to further mature before adding huge cache modules.