Common Mistakes in Broadband Router Performance Evaluation (1)

The most important character in bandwidth-to-Narrowband comparison is the word "fast". Therefore, when you buy a Broadband Router, you are very concerned about its performance. In general, it is "fast ". So many people put forward a variety of evidence to prove that their Broadband Router has good performance and is very fast. However, a lot of evidence is often one-sided. When you buy it back and find that the performance is insufficient, it's time to regret it. From a professional perspective, this article analyzes several "evidence" that people often reference and easily mislead people to judge, and tells everyone how to view the evidence objectively, and how to correctly judge the performance of a broadband router.

Evidence 1: CPU clock speed

Statement: "The processor clock speed is 100 M, and the performance is strong. "" The processor clock speed is 133 M, and the performance is much better than M. "" Uses the communications-related CPU. "

Misunderstanding: first, the processor is only a part of the router, especially because it is the core device. The performance of a vro is poor, but the performance of a vro with a better processor is not necessarily good. Just like cooking, there is no fat and thin fresh pork, there is absolutely no good braised pork, but there is a fat and thin fresh pork, there is no good soy sauce, there is no good cook, still can not do a good braised pork. Second, the processor clock speed is only a performance indicator of the processor. To know the processor performance, you must also know whether its bus width is 16-bit or 32-bit), Cache capacity and structure, internal bus structure, single-CPU or multi-CPU distributed processing, computing mode, and so on, these will greatly affect the performance of the processor, and it is no less important than the clock speed. The so-called "use of communications-related CPU" is equivalent to having nothing to say, but it is easy to use professional terms and do not dare to reveal the details, because almost all routers use communications-related CPU resources, the key lies in what kernel is used by the CPU and the internal structure.

Advanced User: In general, m or lower belongs to the lower frequency, M ~ M is medium, and above M is a relatively high frequency. In addition, I would like to ask what core is the processor, such as 80186, ARM7, arm9-, MIPS, or Intel Xscale? What is the Cache capacity? Is single CPU or multi-CPU distributed processing? Be sure not to ask the honest profiteer. 80186. The ARM7 kernel processor is a typical configuration of the first-generation Broadband Router with low performance and is no longer used by mainstream vendors. The core processors of arm9-and MIPS are currently mainstream. The Intel Xscale architecture is an advanced network processor for high-end products. The Cache capacity is 8 K or less, which is usually 16 K, and 32 K or more is large. Generally, a single CPU is used. A multi-CPU distributed processing system is used for advanced processors with high performance. If you are a professional or want to follow up, you can also take a deeper look at the 920 T, 922 T, T, 940T, or enhanced 926E, 946E, 966E, the performance and structure of MIPS vary greatly depending on the type. You can search for the processor model on Google, and then go to the website of the chip manufacturer to check whether it looks good. By the way, let's also look at other people's comments on the chip, different purposes, cannot be completely trusted ).

Evidence 2: memory capacity

Statement: "I have 16 MB of memory. You can see that it is only 8 MB, and the performance is much better than it. "

Misunderstanding: This sentence has two traps. One problem is that memory is also a component of a router, but an important component. Like a processor, the performance of a vro with low memory usage is not good, but the performance of a vro with high memory usage is not necessarily good. The memory is used to store all the data in the operation process. The memory is like setting up a room. A savvy Shanghai woman is good at "Building a dojo in a shell". Useless things will never be placed in the room. Everything is reasonable. Every corner of the room, from the floor to the ceiling, every inch is fully utilized. A 10-to-20-square-meter apartment can place all the furniture and appliances required by the family, and even have space for one or two potted plants. But if you change to a lazy bachelor, you can give him a set of two-bedroom and as many furniture and appliances as possible, so that he won't be able to put it down, and there will be garbage everywhere in the room in a few days, there is no such thing as a foothold. Therefore, it is unreasonable to judge the performance of a vro based on the size of the memory used. It is equally important to use the memory scientifically. High-level software design can well plan and use the memory, low-level, even without the ability to design, directly use the reference software provided by the processor chip manufacturer without optimization, the memory cannot be effectively planned and used. Two traps are: memory unit and memory bus. Memory can use Byte bytes) as the unit, or Bit) as the unit, the difference between the two, the capacity difference is 8 times 1 Byte = 8 Bit ), generally, B is written in uppercase to indicate Byte, while B is written in lowercase to indicate Bit. However, some people with ulterior motives will do their work here, as shown in the preceding example, it was also intended to mark B over the sea. The memory bus has a narrow width and needs to store or take 4 bytes of data in the memory. If it is a 16-bit memory, it needs to be operated twice, and the 32-bit memory only needs to be operated once, the efficiency is doubled. Therefore, even if the bus width is different for memory of the same capacity, the impact on the router performance is also significant.

Advanced User: Generally, 1 Mbit/s ~ 4 M Byte is small, 8 M Byte is medium, 16 M Byte or above is large. In addition, if someone only tells you how many MB it is, be sure to ask whether it is Byte or Bit, whether it is 16-Bit or 32-Bit. Of course, you have to ask trusted people. Never be cheated. If you are a professional or want to investigate the problem, enter the memory model to Google to search for it, and then go to the website of the chip manufacturer to look good, it will be absolutely not wrong, unless criminals use a polishing chip to fake the chip silk screen. Therefore, it is very important to choose honest and trustworthy manufacturer products.

Evidence 3: Flash capacity

Statement: "My Flash capacity is large, and the performance is better than it. "

Misunderstanding: No reason. Flash is used to store operating systems and applications. The size of Flash depends on the operating system used, the writing efficiency of applications, and the fancy user interface. If an efficient real-time operating system such as VxWorks, Ecos, and Nucleus is selected, the designer has a profound understanding of the operating system and can properly crop it, the designer's application programming efficiency is also very high, you can use small-capacity Flash. If you choose an inefficient operating system such as Linux, the designer does not understand the operating system, and the application programming efficiency is low, or it simply copies the unoptimized reference software provided by the chip manufacturer, you can only use large-capacity Flash. From this point of view, the less Flash is used, the higher the level of software, the more trustworthy the product. Of course, there are many features and user interfaces. If there are many high-definition images, Flash will be a little larger.

Advanced Users: ordinary users do not need to know how big Flash is. As long as they want to see whether the function meets their needs, they can look at the user interface at most, if you have such preferences, it is enough. If you are a professional or want to follow up, you can try to ask the manufacturer what operating system they are using, whether the software is written or copied by yourself, but basically you will be confused, this is the manufacturer's secret.