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How “latency numbers everybody should know” decreased from 1990–2020

colin-scott.github.io

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Re: How “latency numbers everybody should know” decreased from 1990–2020

#41

Post by bmitc »

morelisp wrote: post #15
bmitc wrote: post #13

Today I learned that I don't know any of these numbers that "every" programmer should know. Where do I turn in my programmer card, Jeff Dean?

You could take this instead as an opportunity to learn them, instead of reveling in your ignorance.

There is plenty I don't know. It's not me reveling in my ignorance.

My point is that programming is an incredibly diverse field and yet people, even people who supposedly should know better, are obsessed with making global laws of programming. I know relative comparisons of speeds that have been useful in my day jobs, but I'd wager that needing to know the details of these numbers, how they've evolved, etc. is a relatively niche area.

Regarding learning, I try to constantly learn. This is driven by two things: (1) need, such as one finds in their day job or to complete some side project; (2) interest. If something hits either need or interest or hopefully both, I learn it.

Re: How “latency numbers everybody should know” decreased from 1990–2020

#42

Post by ianai »

ChuckMcM wrote: post #34
ianai wrote: post #21

Earlier quoted context omitted.

"And that means Amdahl's Law is more important than Moore's Law these days." idk, sure seems like we could have 1-2 cores (permanently pegged?) at 5 ghz for UI/UX then ($money / $costPerCores) number of cores for showing off/"performance" by now. But the OEMs haven't gone that way.

We probably see things differently. As I understand it, this is exactly the use case for "big/little" microarchitectures. Take a number of big fast cores that are running full bore, and a bunch of little cores that can do things for them when they get tasked. So far they've been symmetric but with chiplets they needn't be.

Yes, for 'computational' loads. I've read though UI/UX benefits the most from fastest response times. I'm talking about the cores which actually draw the GUI the user sees/uses being optimized for the task at the highest possible rate. Then have a pool of cores for the rest of it.

Re: How “latency numbers everybody should know” decreased from 1990–2020

#43

Post by bee_rider »

ianai wrote: post #21
ChuckMcM wrote: post #17

Not an intuitive thing but the data is fascinating. A couple of notes of people who are confused by it: 1) The 'ns' next to the box is a graph legend not a data label (normally that would be in a box labeled legend to distinguish it from graph data) 2) The weird box and rectangle thing on the top is a slider, I didn't notice that until I was looking at the code and said "what slider?" 3) The only changes from 2005 to…

"And that means Amdahl's Law is more important than Moore's Law these days." idk, sure seems like we could have 1-2 cores (permanently pegged?) at 5 ghz for UI/UX then ($money / $costPerCores) number of cores for showing off/"performance" by now. But the OEMs haven't gone that way.

I would rather reserve the thermal headroom for actual computations, rather than having those cores pegged at 5Ghz.

Re: How “latency numbers everybody should know” decreased from 1990–2020

#45

Post by [deleted] »

gameswithgo wrote: post #28
ChuckMcM wrote: post #17

Not an intuitive thing but the data is fascinating. A couple of notes of people who are confused by it: 1) The 'ns' next to the box is a graph legend not a data label (normally that would be in a box labeled legend to distinguish it from graph data) 2) The weird box and rectangle thing on the top is a slider, I didn't notice that until I was looking at the code and said "what slider?" 3) The only changes from 2005 to…

There is some improvement from processors being faster, as more instructions are done at once and more instructions get down towards that 1ns latency that l1 caches provide. You see it happen in real life but the gains are small.

[deleted]

Re: How “latency numbers everybody should know” decreased from 1990–2020

#46

Post by stuartmscott »

ChuckMcM wrote: post #17

Not an intuitive thing but the data is fascinating. A couple of notes of people who are confused by it: 1) The 'ns' next to the box is a graph legend not a data label (normally that would be in a box labeled legend to distinguish it from graph data) 2) The weird box and rectangle thing on the top is a slider, I didn't notice that until I was looking at the code and said "what slider?" 3) The only changes from 2005 to…

> And that means Amdahl's Law is more important than Moore's Law these days.

100%, we can no longer rely on faster processors to make our code faster, and must instead write code that can take advantage of the hardware's parallelism.

For those interested in learning more about Why Amdahl's Law is Important, my friend wrote an interesting article on this very topic - https://convey.earth/conversation?id=41

Re: How “latency numbers everybody should know” decreased from 1990–2020

#47

Post by muh_gradle »

ChuckMcM wrote: post #17

Not an intuitive thing but the data is fascinating. A couple of notes of people who are confused by it: 1) The 'ns' next to the box is a graph legend not a data label (normally that would be in a box labeled legend to distinguish it from graph data) 2) The weird box and rectangle thing on the top is a slider, I didn't notice that until I was looking at the code and said "what slider?" 3) The only changes from 2005 to…

I would never have realized the slider functionality until I read this comment.

Re: How “latency numbers everybody should know” decreased from 1990–2020

#48

Post by dsr_ »

toqy wrote: post #44
kens wrote: post #27

Amazing performance improvements, except no improvement at all on the packet roundtrip time to Netherlands. Someone should really work on that.

We really need to go back to 1 supercontinent

Direct point to point conduits carrying fiber would reduce latency to a worst case of 21ms, but requires a fiber that doesn't melt at core temps (around 5200C).

Re: How “latency numbers everybody should know” decreased from 1990–2020

#49

Post by pjc50 »

ChuckMcM wrote: post #17

Not an intuitive thing but the data is fascinating. A couple of notes of people who are confused by it: 1) The 'ns' next to the box is a graph legend not a data label (normally that would be in a box labeled legend to distinguish it from graph data) 2) The weird box and rectangle thing on the top is a slider, I didn't notice that until I was looking at the code and said "what slider?" 3) The only changes from 2005 to…

It also tells us that the speed of light has not increased.

(well, speed of signal on a PCB track is roughly 2/3 light and determined by the transmission line geometry and the dielectric constant, but you all knew that)

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