System information

9 Benchmarks and Verification
effect on the processing time. The reason for the low impact of the number of video planes
used is the marking of the so-called dirty regions during the VGA processing that requires
significant amount of processing time. The dirty regions function is used to improve the
screen generation and is explained in the next section.
The next section discusses also the impact of the VGA processing on the PCI throughput.
Figure 9.2: Processing time of the Request Buffer in relation to the running video mode.
Impact of the VGA Processing to the PCI Throughput
Section 9.1.2 discusses the throughput of the PCI target interface without data processing.
This section examines the influence of video data processing to the PCI throughput. Video
data processing depends on two parameters: the video mode and the state of the VNC
server. However, the processing of the incoming VGA data runs independently from the
screen generation of the VNC server. But the VNC server requires I/O bandwidth and
CPU processing time which affects the processing of the VGA driver. Furthermore, the
VNC server only converts new VGA data into the VNC framebuffer. Hence, the number of
incoming VGA data increases the processing time of the VNC server.
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