Method and system for acquiring inner core jiffies from user mode program

Abstract

The invention provides a method for acquiring an inner core jiffies from a user mode program. The method is characterized by including the following steps that firstly, a memory is applied for in an inner core and used for storing the numerical value of the inner core global variable jiffies, the initial address of the memory is set as kmem, 1 will be added to the numerical value of the jiffies every time when clock interrupt of the inner core happens, and the numerical value of the jiffies will be written into the kmem by the inner core as long as the jiffies changes; secondly, the virtual initial address kmem of the memory is converted to a physical initial address kphy by the inner core; thirdly, the physical initial address kphy of the memory is acquired through the user mode program; fourthly, the physical initial address kphy of the memory is converted to a virtual initial address uvir adopted by the user mode program by the user mode program; fifthly, the numerical value of the inner core local variable jiffies stored in the kmem address by the inner core is acquired by the user mode program by reading the virtual initial address uvir. By means of the method, the inner core jiffies can be quickly and conveniently acquired from the user mode program, and accordingly system time can be quickly acquired.

Description

technical field [0001] The invention relates to the technical field of computers, in particular to a method and a system for obtaining kernel jiffies by a program in a user mode. Background technique [0002] The Linux kernel has a global variable called jiffies which represents the number of time ticks since the machine was started. This variable is initially initialized to 0 and is incremented by 1 each time the clock is interrupted. The kernel presets the frequency of the system timer (tick rate) by programming. Each cycle is called a beat. The core frequency is usually 1000Hz, which is 1000 beats per second. Time and relative time can be calculated by jiffies and tick rate. For example, the time period of 2 seconds can be expressed as 2*tick rate, then the time after two seconds can be expressed as jiffies+2*tick rate, it can be seen that the current time and the time after N seconds can be reached through jiffies, so that Provides a benchmark time that can be accurat...

AI Technical Summary

Problems solved by technology

[0004] Existing user-mode programs need to obtain the reference time through the time or local time programming interface, but these interfaces will generate system calls. If the time is obtained frequently, the performance and efficiency of the entire user-mode program will become extremely low

Images