Timekeeping method using mixed clock source

Abstract

The invention discloses a timekeeping method using a mixed clock source. The method includes a hardware clock source selection and a software initialization operation. The hardware clock source selection includes that an internal clock source selects a million instructions per second (MIPS) clock source and is used for Clock Event of a non-zero central processing unit (CPU) in a tickless timekeeping mode, and an external clock source selects a high precision event timer (HPET) clock source and is used for Clock Event and Clock Source in a periodic timekeeping mode, Clock Event of a zero CPU in the tickless timekeeping mode and Clock Source in the tickless timekeeping mode. The software initialization operation includes the steps that 1) CPU initialization is performed; 2) the MIPS clock source is registered as Clock Event by each of CPU cores; 3) the MIPS clock source is registered as Clock Source; 4) system device initialization is performed; 5) the HPET clock source is registered as Clock Event by a non-zero core; 6) the HPET clock source is registered as Clock Source; and 7) dynamic core regulation and automatic frequency conversion mechanisms are started. The method simultaneously supports traditional periodic timekeeping modes and recent tickless timekeeping modes.

Description

technical field [0001] The invention relates to a timing method using a mixed clock source, belonging to the field of computer operating systems. Background technique [0002] The operating system is the manager of the computer. As a manager, the operating system needs to maintain time, that is, timekeeping. The most basic function of timing is to obtain the "current time" (Time Of Day, referred to as TOD), and many operating system functions such as process scheduling, software timers, performance sampling statistics, and Network Time Protocol (NTP) are based on the concept of TOD. Up. [0003] The realization of the timing function depends on the "clock source" device on the hardware. For a clearer expression, the related concepts are listed as follows: [0004] Beatless / periodic clock mode: Periodic mode is a traditional timing mode. In this mode, the hardware clock source periodically emits clock interrupts as the main basis for timing. In a multi-core or multi-proce...

AI Technical Summary

Problems solved by technology

[0013] 2. Interrupt controller: ClockEvent requires each CPU core to receive clock interrupts, but due to the limitations of some interrupt controllers, non-zero cores may not be able to receive interrupts, so in this case, ClockEvent cannot use an external clock source

Frequent corrections not only waste resources, but also bring large cumulative errors to timing

Images