Linux Optimization Process Chapter

Process classifications in Linux systems:

Interactive process (IO-intensive)

Batch process (CPU intensive)

Real-time process (daemon)

Balanced process IO-intensive and CPU-intensive methods:

High priority for IO-intensive: Short CPU time slices

For CPU-intensive: time slices are longer, with lower priority

Process Priority :

Divided into real-time process priority, static process priority, dynamic process priority

Real-time Process priority: 1-99 (the smaller the number, the lower the priority), typically the process associated with the system kernel

Static priority: 100-139 (the smaller the number, the higher the priority), which is generally the process of user-space

Real-time process priority is higher than static priority

Dynamic priority: When a process is not running for a long time, the kernel temporarily prioritizes the process;

When the process is too resource-intensive, the priority is lowered. (The object is typically 100-139 of the process)

To adjust the process priority level:

When a process is created, its default priority is 120, at which point the Nice value is 0,nice with a value range of 20 to 19, and a total of 40 levels. The smaller the value, the higher the process priority, and the higher the value, the lower the priority. You can change the nice value of a process that will be executed with the nice command, or modify the nice value of the executing process through the Renice command

Nice-n bash #将bash的nice值修改为10 with a priority of 130renice 5 bash #将正在运行中的bash进程的nice值加5

scheduling policy for the process :

When the priority of two processes is the same, a certain scheduling policy is required

Real-time process scheduling policy:

Sched_fifo: In the first-in-one-out queue scheduling, in the same priority situation, who first executed the

Who is dispatched first unless it exits or actively releases the CPU.

SCHED_RR: Multiple processes of the same priority are processed in a time-slice rotation.

Non-real-time process scheduling policy:

Sched_other, Sched_idle

To view and set scheduling policies for a process using the CHRT command

Usage: chrt [options]-P [Specify priority] PID

Options

-F Scheduler set to Sched_fifo

-O Scheduler set to Sched_other

-R Scheduler set to SCHED_RR

[Email protected] ~]# chrt-p 34735 #查看pid为34735的进程属性pid 34735 ' s current scheduling policy:sched_otherpid 34735 ' s cur Rent scheduling priority:0

# chrt-f-P #将PID 1000 process is set to SCHED_FIFO, with priority set to 50. # Chrt-o-P 0 #将PID 1000 process is set to Sched_other with priority set to 0. # chrt-f 50/bin/test.sh #启动/bin/test.sh set to Sched_fifo, priority set to 50

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Linux Optimization Process Chapter