Fillrate

The term fillrate usually refers to the number of pixels a video card can render and write to video memory in a second. In this case, fillrates are given in megapixels per second or in gigapixels per second (in the case of newer cards), and they are obtained by multiplying the number of raster operations (ROPs) by the clock frequency of the graphics processor unit (GPU) of a video card. However, there is no agreement on how to calculate and report fillrates. Other possible methods are: to multiply the number of texture units by the clock frequency, or to multiply the number of pixel pipelines by the clock frequency. The results of these multiplications correspond to a theoretical number. The actual fillrate depends on many other factors. In the past, the fillrate has been used as an indicator of performance by video card manufacturers such as ATI and NVIDIA, however, the importance of the fillrate as a measurement of performance has declined as the bottleneck in graphics applications has shifted. For example, today, the number and speed of pixel shader units has gained attention.