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The dynamic power (switching power) dissipated by a chip is C·V 2 ·A·f, where C is the capacitance being switched per clock cycle, V is voltage, A is the Activity Factor [1] indicating the average number of switching events per clock cycle by the transistors in the chip (as a unitless quantity) and f is the clock frequency.
For example, an IBM PC with an Intel 80486 CPU running at 50 MHz will be about twice as fast (internally only) as one with the same CPU and memory running at 25 MHz, while the same will not be true for MIPS R4000 running at the same clock rate as the two are different processors that implement different architectures and microarchitectures ...
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. Common methods are reducing the clock speed along with the CPU voltage and sending parts of the processor into a sleep state.
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 ...
At first, each CPU chip ran in its own single clock domain, and the rest of the digital logic of the computer ran in another slower clock domain. A few modern CPUs have such a high speed clock, that designers are forced to create several different clock domains on a single CPU chip.
An Intel November 2008 white paper [10] discusses "Turbo Boost" technology as a new feature incorporated into Nehalem-based processors released in the same month. [11]A similar feature called Intel Dynamic Acceleration (IDA) was first available with Core 2 Duo, which was based on the Santa Rosa platform and was released on May 10, 2007.
CPU time (or process time) is the amount of time that a central processing unit (CPU) was used for processing instructions of a computer program or operating system. CPU time is measured in clock ticks or seconds. Sometimes it is useful to convert CPU time into a percentage of the CPU capacity, giving the CPU usage.
If the OS timer and the CPU run on two independent clock crystals the situation is ideal and more or less the same as the previous example. But even if they both use the same clock crystal the process /program that does the clock drift measurement is "disturbed" by many more or less unpredictable events in the CPU such as interrupts and other ...