Single core operating system
Generally, it refers to an operating system with a single-core processor, which is used in early electronic products such as computers and mobile phones. With the gradual popularization of multi-core processors in recent years, single-core operating systems are gradually replaced by dual-core or multi-core high-speed processing capabilities. The development from single-core processor to multi-core processor is a major change in the history of processor development.
The so-called "micronucleus" means that only a small part of the operating system runs with the highest priority, and other functions are based on.
If human society is used as a metaphor, CPU stands for execution, which is an abstract concept; The operating system is governments at all levels, and the core of the operating system is the highest decision-maker, which used to be the emperor and prime minister (now the president) and a team around them.
In ancient times, CPU had no privilege level (only x86 series was analyzed here, and the original 8086/8088 had only one real model, and there was no privilege level), just like in the ancient Yao Shunyu era: it was said that even Dayu had to do it himself, because mud came into the water every day, so that there was no long hair on his calf.
Later, smart people found that the system had efficiency problems. There is a description in Han Fei's article "Farmers Invasion on the Shore of Mount Li", saying that in the place where Shun cultivated: Mount Li, people who cultivated in Mount Li invaded other people's farmland, so Shun went there to cultivate, and after one year, the farmland was no longer destroyed and occupied. (Lishan farmers invaded the shore and went to plow, and the period was good. ), and then the people fishing in the river had an argument, so Shun went fishing there. A year later, older people were allowed to occupy the most favorable waters. The artificial pottery made in Dongyi was poor and not strong, so Shun went there to make pottery. A year later, the pottery was very strong. As soon as such civil disputes appeared, Shun set an example to correct folk customs. Han Fei put forward his own views on this, arguing that Shun could not correct infinite mistakes in the world with his limited life. At this time, he must achieve his goal through privilege: even a monarch who is not as wise as Shun can easily execute his death sentence.
The same is true for CPU. In 80286, the protection mode appeared, and the protection mode really began to be practical. It appeared with 80386, and it has been used ever since. Under the design of protected mode, there is a privileged class in CPU, which is what we call Ring0 level, and all instructions executed at Ring0 level are privileged; Our usual programs run at the Ring3 level (Ring 1 and Ring2 levels are not used), which is also called user mode. In this way, the code of the operating system runs at the Ring0 level (and some viruses), and the general program runs at the Ring3 level. Ordinary programs can call the functions of the operating system, just as we can go to the government to redress grievances, they are all handled by the administrative and civil affairs departments of governments at all levels, but the handling process is generally for us.
In protected mode, the operating system has two design ideas: single-core mode and microkernel mode.
Monolithic kernel's idea is that a large number of government departments are working at the privileged level, which has the advantage of high efficiency within the government, such as the windows series we use, from win95 to vista. Of course, windows also said that they have classified a large number of operating system services into user level, or let users decide whether to load them according to their own conditions: we can configure many services through the control panel, such as SNMP (Simple Network Management Protocol) and Microsoft's own firewall. Unix/linux is also a monolithic kernel system. However, because an invention is a 32-bit scientific operating system (unlike windows, which made a fortune by poor DOS), people even use Xwindows programs to replace the most commonly used graphical interfaces of ordinary users, which is not necessarily less efficient than windows, because graphics workstations such as SGI use UNIX.
The idea of microkernel is to keep only the most basic functional modules of the operating system at the privileged level. A large number of services provided by the operating system run in user mode, and the principle is that the simpler the better, so it is called "microkernel", and now it is mostly used in embedded devices. The operating system only provides system calls related to CPU hardware, such as storage space management, process scheduling and inter-process communication. The idea of micronucleus is very good, but it has been criticized for its low efficiency and has not been widely used.
To put it simply, micronucleus is dissatisfied with the bloated institutions that occupy too many resources, and it is the product of the concept of benefiting the people and the miniaturization of the government; Single-core system emphasizes the efficiency of government implementation, but it also takes up more social resources.
For another example, running a program under the microkernel is a bit like eating a buffet, while the operating system under the monolithic kernel mechanism will provide intimate service for Japanese catering.
Philosophers tell us that contradictions are dialectical unity. Just like RISC, CISC and Chinese and Western medicine, the final result is integration rather than disintegration. The future operating system will certainly absorb the advantages of both and provide more perfect help for us to use computers.
It is reported that almost all donations from Wenchuan earthquake have been included in the Ministry of Finance, and how to use them is up to the government. However, most non-governmental charities can't operate because of financial problems, so that they have evacuated from the disaster area.