Search results
Results from the WOW.Com Content Network
Intel C8253 Intel 8253 programmable interval timer. Intel 8254 has the same pinout. The Intel 8253 and 8254 are programmable interval timers (PITs), which perform timing and counting functions using three 16-bit counters. [1] The 825x family was primarily designed for the Intel 8080/8085-processors, but were later used in x86 compatible systems.
The Intel 8253 PIT was the original timing device used on IBM PC compatibles. It used a 1.193182 MHz clock signal (one third of the color burst frequency used by NTSC , one twelfth of the system clock crystal oscillator , [ 1 ] therefore one quarter of the 4.77 MHz CPU clock) and contains three timers.
(Before Windows 8 claimed exclusive rights to this timer, it was also used by some programs like CPU-Z.) Under Microsoft Windows the APIC timer is not a shareable resource. [11] The aperiodic interrupts offered by the APIC timer are used by the Linux kernel tickless kernel feature. This optional but default feature is new with 2.6.18.
The references to two timers is not true. In Intel ICH4 documentation, the timer exists in IO ports 40h..43h, and the same timer is aliased to IO ports 50h..53h for some reason. A very good guess would be that the original IBM PC had it like this too to simplify IO address decoding, but this is just a guess.
The Time Stamp Counter was once a high-resolution, low-overhead way for a program to get CPU timing information. With the advent of multi-core/hyper-threaded CPUs, systems with multiple CPUs, and hibernating operating systems, the TSC cannot be relied upon to provide accurate results — unless great care is taken to correct the possible flaws: rate of tick and whether all cores (processors ...
The documentation of Red Hat MRG version 2 states that TSC is the preferred clock source due to its much lower overhead, but it uses HPET as a fallback. A benchmark in that environment for 10 million event counts found that TSC took about 0.6 seconds, HPET took slightly over 12 seconds, and ACPI Power Management Timer took around 24 seconds. [6]
Grindstone is a freeware Microsoft Windows desktop application that allows users to create and organize tasks and to track time.The application features a Task List window for managing tasks and time, a desktop gadget-like stopwatch for controlling the timer, and can produce reports and detect when the user is away.
A tickless kernel is an operating system kernel in which timer interrupts do not occur at regular intervals, but are only delivered as required. [1]The Linux kernel on s390 from 2.6.6 [2] and on i386 from release 2.6.21 [3] can be configured to turn the timer tick off (tickless or dynamic tick) for idle CPUs using CONFIG_NO_HZ, and from 3.10 with CONFIG_NO_HZ_IDLE extended for non-idle ...