John Carmack explains why its faster to send a packet to Europe

first_imgYou might know John Carmack as the guy behind Id Software (makers of Wolfenstein, Doom, Quake, and most recently Rage), but he’s also one of those eccentric rich fellows involved in private aerospace. Carmack recently tweeted something perplexing that seems impossible on the face of it. “I can send an IP packet to Europe faster than I can send a pixel to the screen. How f’d up is that?” the post read. Happily, Carmack was good enough to expand on his claim, and he has the data to back it up.You’re probably familiar with the use of ping to determine connection response time, but that is a two way communication — the actual time to send data is half of your ping. Ping can easily be somewhere south of 100ms with a reasonably good connection, so it might take 50ms or less to send your packet. Getting a pixel on a screen is a much more convoluted process.Carmack used a desktop program to cycle colors on his display each time a button was pressed. Using a 240fps camera, he was able to count the frames to determine how long it took the button press to become a pixel on the screen. Using his Sony-made head mounted display, Carmack calculated the latency to be over 70ms. That could be easily longer than the time to send a packet across the world.Modern monitor technologies, despite having their own advantages, tend to have more lag than classic CRT screens did. A CRT can paint a pixel on the screen about 5-10 times faster than an LCD, depending on the quality of the display. In this case it took just 2 frames, or 8-10ms, for the signal to reach the CRT screen.With LCDs, there is also the loss of time from HID processing, input path latency, and time for the LCD panels to physically flip around. You can be standing around tapping your foot for a totally unreasonable 4-20ms just waiting for the LCD panels to change. Adding additional screens or post-processing effects will add additional frames to your wait due to video driver lag. It all adds up to a transatlantic packet being speedier than your own computer monitor.Carmack notes that an OLED screen, where all the light emitted is coming directly from the pixels themselves, is much faster. An Emagin z800 Carmack tested has latency comparable to a 60Hz LCD, which is impressive. Of course, large OLED panels are rare and often very pricey.Not all LCDs will be as poor as the Sony device John Carmack tested, but 40-50ms is about as good as LCDs can do. If you ping a faraway server, and divide by two, you could find that you too can outrun your pixels with the Internet.via SuperUserlast_img read more

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