In the smp system, what mechanisms are provided by the operating system?

SMP (Symmetric Multi-Processing), the abbreviation of symmetric multi-processing structure, refers to a group of processors (multiple CPUs) assembled on a computer, and the memory subsystem is shared between each CPU. and bus structure. With the support of this technology, a server system can run multiple processors at the same time and share memory and other host resources. Like dual Xeon, which is what we call two-way, this is the most common type in symmetric processor systems (Xeon MP can support up to four-way, AMD Opteron can support 1-8 way). There are also a few that are number 16. But generally speaking, the scalability of machines with SMP structure is poor, and it is difficult to achieve more than 100 multi-processors. The conventional ones are generally 8 to 16, but this is enough for most users. It is most common in high-performance server and workstation-class motherboard architectures, such as UNIX servers that can support systems with up to 256 CPUs.

The necessary conditions for building an SMP system are: hardware supporting SMP including motherboard and CPU; system platform supporting SMP, and application software supporting SMP.

In order to enable the SMP system to perform efficiently, the operating system must support SMP systems, such as 32-bit operating systems such as WINNT, Linux, and UNIX. That is, capable of multitasking and multithreading. Multitasking means that the operating system can enable different CPUs to complete different tasks at the same time; multithreading means that the operating system can enable different CPUs to complete the same task in parallel.

To set up an SMP system, there are very high requirements for the selected CPU. First, the APIC (Advanced Programmable Interrupt Controllers) unit must be built inside the CPU. The core of the Intel multiprocessing specification is the use of Advanced Programmable Interrupt Controllers (APICs); again, the same product model, the same type of CPU core, the exact same operating frequency; finally, keep it as the same as possible Product serial number, because when two production batches of CPUs are run as dual processors, it may happen that one CPU is overloaded and the other is underloaded very little, unable to exert maximum performance, or worse. It may cause a crash.

Another answer: SMP: Symmetric MultiProcessing, that is, symmetric multi-processing. Refers to a group of processors (multiple CPUs) assembled on a computer. They share the memory and bus structure, and the system symmetrically distributes the processing task queues on multiple CPUs, thus greatly improving the system's data processing capabilities. With the improvement of application level, it is difficult for a single processor to meet actual application requirements, so server manufacturers have adopted symmetric multi-processing systems to solve this contradiction. The most common symmetric multi-processing systems in PC servers use 2-way, 4-way or 8-way processors. UNIX servers can support up to 64 CPU systems, such as Sun's product E10000. The most critical technical issue in the SMP system is how to better solve the coordination and communication of multi-processors.

Reprinted from: /nangong127@126/blog/static/38590245200781195434667/