Thus, the CPU performance depends on three parameters: the clock cycle (or frequency), the average number of cycles per command, and the number of commands executed. With a certain number of executable commands in the program, this parameter allows you to quickly estimate the CPU time for this program. Thus, the CPU time for some program can be expressed in two ways: the number of clock cycles for a given program, multiplied by the duration of the synchronization clock, or the number of clock cycles for a given program divided by the synchronization frequency.Īn important characteristic, often published in the reports on processors, is the average number of clock cycles per command - CPI (clock cycles per instruction). The length of the synchronization period is the inverse of the synchronization frequency. Computer designers usually talk about a synchronization period, which is determined either by its duration (for example, 10 nanoseconds) or by the frequency (for example, 100 MHz). Discrete time events are called clock cycles, ticks, clock periods, cycles, or clock cycles. In most modern processors, the speed of the processes of interaction of internal functional devices is determined not by natural delays in these devices, but is determined by a single system of clock signals generated by some clock generator, usually operating at a constant speed. Therefore, when measuring the processor's performance, the amount of user and system CPU time is often used.
#Linpack benchmark report table 1. code
On the other hand, the system code on some machines is the user code on others and, in addition, almost no program can work without some operating system. In some cases, the system time of the CPU is ignored because of the possible inaccuracy of the measurements performed by the operating system itself, and also because of the problems associated with comparing the performance of machines with different operating systems. The CPU time can be further divided by the time spent by the CPU directly on the execution of the user program and called the CPU user time, and the CPU time spent by the operating system on the execution of the tasks requested by the program, and called CPU time. Obviously, the response time seen by the user is the total execution time of the program, not the CPU time. To measure the processor's operating time, a special parameter is used in this program - CPU time, which does not include the I / O timeout or the execution time of another program. However, when working in multiprogram mode while waiting for I / O for one program, the processor can execute another program, and the system will not necessarily minimize the execution time of this particular program. This is a delay in the task, which includes literally everything: processor operation, disk accesses, memory accesses, I / O and operating system overhead. The simplest way to determine time is called astronomical time, response time, execution time, or elapsed time. However, depending on what we believe, time can be determined in various ways. Often, performance is measured as the rate of occurrence of a certain number of events per second, so a shorter time implies greater performance. The execution time of any program is measured in seconds. The unit of measurement of computer performance is time: a computer that performs the same amount of work in less time is faster. They allow developers and users to choose between alternatives based on quantitative indicators, which allows for continuous progress in this area. In the development of computer technology, several such standard techniques have emerged. The basis for comparing different types of computers with each other is given by standard methods of measuring productivity. Estimating the performance of computing systems
0 kommentar(er)
