Search results
Results From The WOW.Com Content Network
Idle is a state that a computer processor is in when it is not being used by any program. Every program or task that runs on a computer system occupies a certain amount of processing time on the CPU. If the CPU has completed all tasks it is idle. Modern processors use idle time to save power.
In Windows NT operating systems, the System Idle Process contains one or more kernel threads which run when no other runnable thread can be scheduled on a CPU. In a multiprocessor system, there is one idle thread associated with each CPU core. For a system with hyperthreading enabled, there is an idle thread for each logical processor.
Typical values for L/E range from 0.01 to 0.1. [3] In a system with a L/E ratio of 0.05, for instance, if there are 15 CPUs, it is expected that on average 1 CPU will always be idle; [3] with 21 CPUs, 2.8 will be idle; [4] with 40 CPUs, 19 will be idle; with 41 CPUs, 20 will be idle. [3] Therefore, adding more than 40 CPUs to that system would ...
An idle computer has a load number of 0 (the idle process is not counted). Each process using or waiting for CPU (the ready queue or run queue) increments the load number by 1. Each process that terminates decrements it by 1. Most UNIX systems count only processes in the running (on CPU) or runnable (waiting for CPU) states.
For example, hardware timers send interrupts to the CPU at regular intervals. Most operating systems execute a HLT instruction when there is no immediate work to be done, putting the processor into an idle state. In Windows NT, for example, this instruction is run in the "System Idle Process". On x86 processors, the opcode of HLT is 0xF4.
The CPU-bound process will get and hold the CPU. During this time, all the other processes will finish their I/O and will move into the ready queue, waiting for the CPU. While the processes wait in the ready queue, the I/O devices are idle. Eventually, the CPU-bound process finishes its CPU burst and moves to an I/O device.
CPU Idle: 0x05: Requests system suspend. 0) Clock halted until timer tick interrupt. 1) Slow clock [1] CPU Busy: 0x06: Driver tells system APM to restore clock speed of the CPU. Set Power State: 0x07: Set system or device into Suspend/Standby/Off state. Enable/Disable Power Management: 0x08: Restore APM BIOS Power-On Defaults: 0x09: Get Power ...
Runahead is a technique that allows a computer processor to speculatively pre-process instructions during cache miss cycles. The pre-processed instructions are used to generate instruction and data stream prefetches by executing instructions leading to cache misses (typically called long latency loads) before they would normally occur, effectively hiding memory latency.