6 ms·

Transatlantic ping faster than sending a pixel to the screen? (2012)

104 points by notRobot 5y ago

adolph 5y ago
This is a classic and wonderful way to learn and think about the junction of physics and computers. Another one is https://news.ycombinator.com/item?id=702713 https://news.ycombinator.com/item?id=702713
- OJFord 5y ago
  Gosh that's a fun read in all sorts of ways. SSDs are relatively new, there are hold-outs, and they cost $300 for 80GB!
  - walrus01 5y ago
    At right around the time that was published in 2009, I bought a new 17 inch MacBook pro and a $350 Intel 80GB 2.5" SATA ssd, and stuck the SSD into the position formerly occupied by the dvdrw in a special holder. Worked great as boot drive.
- anthropodie 5y ago
  Imgur has has become so horrible that it loaded all recommendations first and it had still not loaded the main content before I closed the tab. I wish this was hosted somewhere else.
  - tyingq 5y ago
    Never loaded for me. Alternate site: https://ibb.co/HHgRSG8 https://ibb.co/HHgRSG8
- marcosdumay 5y ago
  That image would be better by having an year tag. Since then the ratios increased (L1 to RAM by quite a bit), SSD became common, and networks got intermingled with everything.
  - usr1106 5y ago
    Or having a series of images every 5-10 years. Or have factors changed so little that not much additional would be shown?
stygiansonic 5y ago
RTINGS.com has a decent database of displays sorted by input lag (which is the topic of this post): https://www.rtings.com/monitor/tests/inputs/input-lag https://www.rtings.com/monitor/tests/inputs/input-lag
breakingcups 5y ago
Note that John Carmack himself provided that answer.
ksec 5y ago
I have always been crying about latency computing for years. My earliest HN comment on the topic was in 2012. And I have been ranting about it for even longer outside I really hope at the later part of this decade we start focusing on latency computing instead of bandwidth. From Display, Input, Output and Network, and down to OS and Software. I had always hoped VR would forced those optimisation due to VR being a latency sensitive, as John Carmack was doing at the time. But VR never happened.
- hhhhhklkkliiii 5y ago
  VR never happened? Someone needs to let Valve and Oculus know..
  - emteycz 5y ago
    Well it certainly did not happen in way other technologies happened - smartphones, social networks, laptops, desktops... VR is definitely slower and smaller market right now than these other devices were after similar number of years.
    - SV_BubbleTime 5y ago
      I’m ok with VR being slow. There is no need to rush it. There are some amazing VR experiences. Half Life Alyx while standing, despite it being a disaster overall VirtaMate can have some really interesting erotic setups, beat saber is the only music game I’ve ever really got into, and… IDK, some things are just not possible outside of VR like SuperHot VR being a totally different everything than it’s normal version. I would like there to be more quality content but sooner, but I think it’s largely in a grey area between hardware not being good enough yet and software being expensive to develop. I used to poopoo it, but I’ve come around that VR is in the cards, just slowly.
    - IshKebab 5y ago
      By that metric almost nothing "happened". And I'd say VR is advancing way faster than desktops, and maybe even the rest of your list. You just don't remember the products that existed when they were still fairly niche, like the iPaq, Amstrad and Friendster.
clktmr 5y ago
Optimizing for latency is often counter-intuitive. Polling as an example may be an effective way to lower latency, e.g. Linux NAPI. Increasing buffer sizes may also decrease latency because data can be processed in bursts, see buffer starvation. But if data comes in at a higher rate than can be processed, buffers fill up and are horrible for latency.
- SV_BubbleTime 5y ago
  > Polling as an example may be an effective way to lower latency, I had to learn this lesson the hard way recently. An embedded system where I had to get data from a couple SPI controller’s RAM. Made a bit complicated ISR and listener system that woke up threads to do a deferred-interrupt… by the time it was all said and done with a fair bit of code, I wasn’t happy with it. I figured out that usually data would be available every 2ms and just wrote the read routine just to sleep every 2ms and attempt another read, I have it “hitting” 90% of the time and my avg latency is almost nothing. .7ms or so.
Veliladon 5y ago
The transatlantic ping is waves traveling at the speed of light in fiber and a large fraction of the speed of light in copper. To send a pixel to a screen you need to wait for the next vsync if you're not using a variable refresh rate display. That alone can be double digit milliseconds. Then you need to wait for the crystals in the screen to physically move in response to applied voltage. Moving things is slow. Moving things happens at speeds far less than the speed of light unless you're putting in enough energy to vaporize a city. If you wait around and rely on things that move extremely slowly compared to the light speed of fiber and near light speed of electrical signals, waiting around for a crystal to turn and align itself to a voltage is going to take an eternity in comparison. So yeah, no shit it's slower to display a pixel.
- mdoms 5y ago
  Perhaps you should read the linked Q&A before commenting.
  - charliebreslau 5y ago
    Wrong. Copper is almost same speed as fiber (~200.000 km/s). Radio signal is fastest ~300.000 km/s. Light travels in fiberglass at 2/3 speed of light (precisely c - speed of light in vacuum - ~300.000 km/s. Same with twisted copper cables.
- klmr 5y ago
  I dunno, I don’t think it’s that obvious: the physical movement in an LCD is across tiny masses and distances (at molecular scale); the network signal has to cross a distance that’s many orders of magnitude larger. Comparing these two things without looking at actual number doesn’t strike me as valid, even for approximations. Furthermore, if I’m reading the RTINGS.com source posted below correctly, modern LCDs have smaller latencies than a transatlantic ping. So not only is it not obvious, it’s no longer universally true.
- cozzyd 5y ago
  Well the effective refractive index of fiber is something like 1.4 or so I think.
walrus01 5y ago
This is one of the reasons why the hardcore retro gaming people are still paying big money for 32" Sony Trinitron analog CRT TVs and such. Ultra low latency from image source to display. If you have a good condition Trinitron like display these days (Mitsubishi diamondtron, sony pvm, etc) it is presently appreciating in value every year.
ChrisArchitect 5y ago
anything new on this? previous discussion from 10 years ago: https://news.ycombinator.com/item?id=3914638 https://news.ycombinator.com/item?id=3914638

104 points by notRobot 5y ago

This is a classic and wonderful way to learn and think about the junction of physics and computers. Another one is https://news.ycombinator.com/item?id=702713 https://news.ycombinator.com/item?id=702713

OJFord 5y ago
Gosh that's a fun read in all sorts of ways. SSDs are relatively new, there are hold-outs, and they cost $300 for 80GB!
- walrus01 5y ago
  At right around the time that was published in 2009, I bought a new 17 inch MacBook pro and a $350 Intel 80GB 2.5" SATA ssd, and stuck the SSD into the position formerly occupied by the dvdrw in a special holder. Worked great as boot drive.
anthropodie 5y ago
Imgur has has become so horrible that it loaded all recommendations first and it had still not loaded the main content before I closed the tab. I wish this was hosted somewhere else.
- tyingq 5y ago
  Never loaded for me. Alternate site: https://ibb.co/HHgRSG8 https://ibb.co/HHgRSG8
marcosdumay 5y ago
That image would be better by having an year tag. Since then the ratios increased (L1 to RAM by quite a bit), SSD became common, and networks got intermingled with everything.
- usr1106 5y ago
  Or having a series of images every 5-10 years. Or have factors changed so little that not much additional would be shown?

stygiansonic 5y ago

RTINGS.com has a decent database of displays sorted by input lag (which is the topic of this post): https://www.rtings.com/monitor/tests/inputs/input-lag https://www.rtings.com/monitor/tests/inputs/input-lag

breakingcups 5y ago

Note that John Carmack himself provided that answer.

ksec 5y ago

I have always been crying about latency computing for years. My earliest HN comment on the topic was in 2012. And I have been ranting about it for even longer outside I really hope at the later part of this decade we start focusing on latency computing instead of bandwidth. From Display, Input, Output and Network, and down to OS and Software. I had always hoped VR would forced those optimisation due to VR being a latency sensitive, as John Carmack was doing at the time. But VR never happened.

hhhhhklkkliiii 5y ago
VR never happened? Someone needs to let Valve and Oculus know..
- emteycz 5y ago
  Well it certainly did not happen in way other technologies happened - smartphones, social networks, laptops, desktops... VR is definitely slower and smaller market right now than these other devices were after similar number of years.
  - SV_BubbleTime 5y ago
    I’m ok with VR being slow. There is no need to rush it. There are some amazing VR experiences. Half Life Alyx while standing, despite it being a disaster overall VirtaMate can have some really interesting erotic setups, beat saber is the only music game I’ve ever really got into, and… IDK, some things are just not possible outside of VR like SuperHot VR being a totally different everything than it’s normal version. I would like there to be more quality content but sooner, but I think it’s largely in a grey area between hardware not being good enough yet and software being expensive to develop. I used to poopoo it, but I’ve come around that VR is in the cards, just slowly.
  - IshKebab 5y ago
    By that metric almost nothing "happened". And I'd say VR is advancing way faster than desktops, and maybe even the rest of your list. You just don't remember the products that existed when they were still fairly niche, like the iPaq, Amstrad and Friendster.

clktmr 5y ago

Optimizing for latency is often counter-intuitive. Polling as an example may be an effective way to lower latency, e.g. Linux NAPI. Increasing buffer sizes may also decrease latency because data can be processed in bursts, see buffer starvation. But if data comes in at a higher rate than can be processed, buffers fill up and are horrible for latency.

SV_BubbleTime 5y ago
> Polling as an example may be an effective way to lower latency, I had to learn this lesson the hard way recently. An embedded system where I had to get data from a couple SPI controller’s RAM. Made a bit complicated ISR and listener system that woke up threads to do a deferred-interrupt… by the time it was all said and done with a fair bit of code, I wasn’t happy with it. I figured out that usually data would be available every 2ms and just wrote the read routine just to sleep every 2ms and attempt another read, I have it “hitting” 90% of the time and my avg latency is almost nothing. .7ms or so.

Veliladon 5y ago

The transatlantic ping is waves traveling at the speed of light in fiber and a large fraction of the speed of light in copper. To send a pixel to a screen you need to wait for the next vsync if you're not using a variable refresh rate display. That alone can be double digit milliseconds. Then you need to wait for the crystals in the screen to physically move in response to applied voltage. Moving things is slow. Moving things happens at speeds far less than the speed of light unless you're putting in enough energy to vaporize a city. If you wait around and rely on things that move extremely slowly compared to the light speed of fiber and near light speed of electrical signals, waiting around for a crystal to turn and align itself to a voltage is going to take an eternity in comparison. So yeah, no shit it's slower to display a pixel.

mdoms 5y ago
Perhaps you should read the linked Q&A before commenting.
- charliebreslau 5y ago
  Wrong. Copper is almost same speed as fiber (~200.000 km/s). Radio signal is fastest ~300.000 km/s. Light travels in fiberglass at 2/3 speed of light (precisely c - speed of light in vacuum - ~300.000 km/s. Same with twisted copper cables.
klmr 5y ago
I dunno, I don’t think it’s that obvious: the physical movement in an LCD is across tiny masses and distances (at molecular scale); the network signal has to cross a distance that’s many orders of magnitude larger. Comparing these two things without looking at actual number doesn’t strike me as valid, even for approximations. Furthermore, if I’m reading the RTINGS.com source posted below correctly, modern LCDs have smaller latencies than a transatlantic ping. So not only is it not obvious, it’s no longer universally true.
cozzyd 5y ago
Well the effective refractive index of fiber is something like 1.4 or so I think.

walrus01 5y ago

This is one of the reasons why the hardcore retro gaming people are still paying big money for 32" Sony Trinitron analog CRT TVs and such. Ultra low latency from image source to display. If you have a good condition Trinitron like display these days (Mitsubishi diamondtron, sony pvm, etc) it is presently appreciating in value every year.

ChrisArchitect 5y ago

anything new on this? previous discussion from 10 years ago: https://news.ycombinator.com/item?id=3914638 https://news.ycombinator.com/item?id=3914638