5 ms·

Soft Orders of Magnitude

39 points by frizlab 3y ago

wly_cdgr 3y ago
Really like this human-centered way of thinking about performance in terms of how it maps to our perception and working rhythms
DylanSp 3y ago
I like this term; I've heard this idea in multiple places before, but this seems like a good way of capturing the essential point (that with performance, a sufficiently large difference in degree can become a difference in kind by enabling new patterns of work).
- jasonhong 3y ago
  If you want something a bit more formal, see Turing Award winner Allen Newell's Bands of Cognition. He breaks things up into four major bands, namely biological (milliseconds), cognitive (seconds), rational (minutes to hours), and social (days to months). Each band requires different tools, as well as ways of thinking about and analyzing them. Here's an example diagram of it: https://www.researchgate.net/profile/Bruno-Emond/publication/44054231/figure/tbl1/AS:394344008830978@1471030346600/Newells-four-bands-of-cognition.png https://www.researchgate.net/profile/Bruno-Emond/publication...
  - avidiax 3y ago
    What does "social" mean in this context? I.e. it means that now the task can be tackled by multiple people or organizations, that this is desirable, or that it should be?
antognini 3y ago
I used to work on hearing aids and there's a similar concept in human audio perception with regard to audio latency. If you add latency to some audio (say because of the hearing aid's processing), the perception that the audio is getting worse doesn't increase smoothly with the latency. Instead there are a few thresholds where the latency seems to be perceptibly worse. The main ones are: 0--2 ms: No perception of latency at all. 2--10 ms: There is a comb filtering effect, so the audio sounds somewhat distorted. 10--30 ms: There's a perception that something is "off" about the audio and it requires greater cognitive effort to listen to. This is partly due to a noticeable desynchronization between the audio and visual cues. Another factor is the "Haas effect." If you have a direct path (audio that goes straight into the ear) and audio coming out of the hearing aid at some latency with respect to the direct path, the arrival of these two separate wavefronts at different times causes a perceptible distortion in the audio. 30+ ms: Beyond this people perceive an actual lag between what they see and the audio they hear. It can be almost nauseating to listen to audio at this latency for long periods of time. The upshot of all this is that if you look at the latencies that hearing aids on the market have, they all cluster into two groups: one at around 2 ms and another at around 10 ms. If you can fit all your processing into 2 ms that's great, but if you go much longer than that, you may as well take the full 10 ms to do even more processing because people aren't going to be able to tell the difference.
onetimeuse92304 3y ago
There is more discernible levels of lagging between "instantly" and "1-2s", and more levels above "a weekend". For example, for about 3 years I worked on a project where I had to send the code I wrote to an external entity to get it compiled and signed before I could run it on my device. It took one week at the minimum. I had to completely change the approach to my personal coding process as well as development process in general. It was so powerful that even to this day I am developing for days without compiling code and people are very surprised it usually runs on the first try -- if you can write in ANSI C for a week and have it running on the first try, doing the same in Java is a piece of cake. Trust me, waiting for a week for your code to run is very different from waiting for a weekend, where you can leave your computer on Friday and plan to conduct your tests on Monday. Other even larger orders of delay concern ability to change things in the environment. For example annoying things like broken process, broken automation, etc. In one company you could be able to fix things on your own, sometimes in minutes. In other companies you could face multi-month wait to get even slightest changes. If you have to wait for a quarter to get a new Jira ticket field you are not very likely to do it or care for the process in general. Then you have the world of shorter delays. Things that take a millisecond will usually already require you to take this into account when you work with it. Can I do this in a loop? Can I recalculate this whenever I need or do I need to cache the value? Etc. Whatever the solution, it costs you a bit of your focus and as we all know, focus is the main resource of software developer. Then you go to 20-50 milliseconds and this is where users notice delays. It is not as snappy as it was even if they can't exactly specify what changed. By the time you get to 200ms, the users will complain the application is slow and irritating, especially if they spend a lot of time in it clicking on things.
- LoganDark 3y ago
  > I am developing for days without compiling code and people are very surprised it usually runs on the first try this is a thing that surprises people? Perhaps I'm not as brave by doing it in Rust, but I can go weeks without compiling code. Rewrite or refactor everything, be done, have it entirely work or only require a couple tweaks.
  - 3y ago
mcqueenjordan 3y ago
Oh man, I was just making an argument for performance goals based off exactly this concept, but I hadn't thought of the framing of "soft orders of magnitude" -- that's a great analogy. Thinking a bit more, I think "paradigm shift" and "discontinuity" also works. Every "soft order of magnitude" is in fact a qualitative shift of the experience -- - "I can reasonably stare at this tool's output and wait for it to finish" - "I'll get distracted and look outside but I won't switch off task." - "Time for a coffee."

39 points by frizlab 3y ago

Really like this human-centered way of thinking about performance in terms of how it maps to our perception and working rhythms

DylanSp 3y ago

I like this term; I've heard this idea in multiple places before, but this seems like a good way of capturing the essential point (that with performance, a sufficiently large difference in degree can become a difference in kind by enabling new patterns of work).

jasonhong 3y ago
If you want something a bit more formal, see Turing Award winner Allen Newell's Bands of Cognition. He breaks things up into four major bands, namely biological (milliseconds), cognitive (seconds), rational (minutes to hours), and social (days to months). Each band requires different tools, as well as ways of thinking about and analyzing them. Here's an example diagram of it: https://www.researchgate.net/profile/Bruno-Emond/publication/44054231/figure/tbl1/AS:394344008830978@1471030346600/Newells-four-bands-of-cognition.png https://www.researchgate.net/profile/Bruno-Emond/publication...
- avidiax 3y ago
  What does "social" mean in this context? I.e. it means that now the task can be tackled by multiple people or organizations, that this is desirable, or that it should be?

antognini 3y ago

I used to work on hearing aids and there's a similar concept in human audio perception with regard to audio latency. If you add latency to some audio (say because of the hearing aid's processing), the perception that the audio is getting worse doesn't increase smoothly with the latency. Instead there are a few thresholds where the latency seems to be perceptibly worse. The main ones are: 0--2 ms: No perception of latency at all. 2--10 ms: There is a comb filtering effect, so the audio sounds somewhat distorted. 10--30 ms: There's a perception that something is "off" about the audio and it requires greater cognitive effort to listen to. This is partly due to a noticeable desynchronization between the audio and visual cues. Another factor is the "Haas effect." If you have a direct path (audio that goes straight into the ear) and audio coming out of the hearing aid at some latency with respect to the direct path, the arrival of these two separate wavefronts at different times causes a perceptible distortion in the audio. 30+ ms: Beyond this people perceive an actual lag between what they see and the audio they hear. It can be almost nauseating to listen to audio at this latency for long periods of time. The upshot of all this is that if you look at the latencies that hearing aids on the market have, they all cluster into two groups: one at around 2 ms and another at around 10 ms. If you can fit all your processing into 2 ms that's great, but if you go much longer than that, you may as well take the full 10 ms to do even more processing because people aren't going to be able to tell the difference.

onetimeuse92304 3y ago

There is more discernible levels of lagging between "instantly" and "1-2s", and more levels above "a weekend". For example, for about 3 years I worked on a project where I had to send the code I wrote to an external entity to get it compiled and signed before I could run it on my device. It took one week at the minimum. I had to completely change the approach to my personal coding process as well as development process in general. It was so powerful that even to this day I am developing for days without compiling code and people are very surprised it usually runs on the first try -- if you can write in ANSI C for a week and have it running on the first try, doing the same in Java is a piece of cake. Trust me, waiting for a week for your code to run is very different from waiting for a weekend, where you can leave your computer on Friday and plan to conduct your tests on Monday. Other even larger orders of delay concern ability to change things in the environment. For example annoying things like broken process, broken automation, etc. In one company you could be able to fix things on your own, sometimes in minutes. In other companies you could face multi-month wait to get even slightest changes. If you have to wait for a quarter to get a new Jira ticket field you are not very likely to do it or care for the process in general. Then you have the world of shorter delays. Things that take a millisecond will usually already require you to take this into account when you work with it. Can I do this in a loop? Can I recalculate this whenever I need or do I need to cache the value? Etc. Whatever the solution, it costs you a bit of your focus and as we all know, focus is the main resource of software developer. Then you go to 20-50 milliseconds and this is where users notice delays. It is not as snappy as it was even if they can't exactly specify what changed. By the time you get to 200ms, the users will complain the application is slow and irritating, especially if they spend a lot of time in it clicking on things.

LoganDark 3y ago
> I am developing for days without compiling code and people are very surprised it usually runs on the first try this is a thing that surprises people? Perhaps I'm not as brave by doing it in Rust, but I can go weeks without compiling code. Rewrite or refactor everything, be done, have it entirely work or only require a couple tweaks.
- 3y ago

mcqueenjordan 3y ago

Oh man, I was just making an argument for performance goals based off exactly this concept, but I hadn't thought of the framing of "soft orders of magnitude" -- that's a great analogy. Thinking a bit more, I think "paradigm shift" and "discontinuity" also works. Every "soft order of magnitude" is in fact a qualitative shift of the experience -- - "I can reasonably stare at this tool's output and wait for it to finish" - "I'll get distracted and look outside but I won't switch off task." - "Time for a coffee."