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Re:Do You Know How Much Your Computer Can Do in a Second? by jstanley on Thursday June 22, 2023 @05:08PM (#36439042)
> Even programmers and IT professionals have literally not mental model of how fast computers really are.

Or of how slow light is!

Re:Do You Know How Much Your Computer Can Do in a Second? by paulddraper on Thursday June 22, 2023 @05:28PM (#36439280)
Exactly.

Speed of light is not exactly a relatable point of reference.

Re:Do You Know How Much Your Computer Can Do in a Second? by jiggawatts on Thursday June 22, 2023 @07:15PM (#36440538)
It ought to be intuitive for everyone working in software development!

The performance of everything is limited in one way or another by ‘c’.

Not just WAN links, but the data centre Ethernet as well. The distance to the disks matters. The physical size of the motherboard. The placement of caches, etc…

When people say things like “putting the compute near the data” they’re implicitly talking about overcoming the limits imposed by the speed of light.

When you hear about an N+1 performance issue in some ORM, that’s bad because of the speed of light.

When you test your LAN with “ping”, you’re lying to yourself because it won’t show measurements below 1 ms, which is an eternity.

I just told you how much compute can occur in just 10 nanoseconds.

Go ping something. Look at the “1 ms” in the output. Go back to my post and work out what can occur in 1,000,000 nanoseconds. Go look at the 1 ms again.

Repeat until you have an epiphany about your zone redundant Kubernetes-hosted cloud native microservices architecture.

Re:Do You Know How Much Your Computer Can Do in a Second? by BenjiWiebe on Thursday June 22, 2023 @09:08PM (#36441471)
FYI the ping utility in linux shows 3 significant figures. On my lan it's reporting 0.156ms avg between two hosts.
Re:Do You Know How Much Your Computer Can Do in a Second? by jiggawatts on Friday June 23, 2023 @04:34AM (#36444286)
150 microseconds is typical, but for reference, Azure gets about 85µs between VMs in proximity placement groups, and I've heard of single-digit latencies with high-end RDMA NICs.

Your ping is 156,000 nanoseconds. You just saw that you can in principle do about 6,400 computations per 30ns, so... that's about 33 million arithmetic calculations per round-trip, within the data centre.

I hope this makes you see every unnecessary network hop in a different light.

PS: It typically takes 3 round-trips to establish a TCP connection, and 5-7 for a TLS connection. A database connection over TLS needs a few more. And then you have load balancers, firewalls, proxies, envoy, ingress, dapr, and, and, and...

Re:Do You Know How Much Your Computer Can Do in a Second? by Dylan16807 on Friday June 23, 2023 @12:25AM (#36442768)
Speed of light between datacenters is important.

Datacenter Ethernet has too much overhead to make a difference in almost all cases. Disks have an even higher overhead:distance ratio. The size of a motherboard only matters for signal integrity, not that half a nanosecond extra. Cache location inside a chip can matter, but even then size is a significantly bigger factor than location.

Re:Do You Know How Much Your Computer Can Do in a Second? by dylan604 on Thursday June 22, 2023 @11:24PM (#36442423)
Except we know nothing is faster than light, so that's a reference people know
Re:Do You Know How Much Your Computer Can Do in a Second? by pyinstallwoes on Friday June 23, 2023 @01:30AM (#36443165)
Unless you don’t measure it, then it’s as fast as it needs to be!

Oh group velocity.

Re:Do You Know How Much Your Computer Can Do in a Second? by elboru on Thursday June 22, 2023 @05:54PM (#36439603)
This site[0] helped me improve my mental model. You can scroll through the solar system at scale (the moon being one pixel). It takes a while!!

Then you notice a small button at the right bottom corner, that button allows you to auto-scroll at the speed of light, wow, now that’s slow!

[0]https://joshworth.com/dev/pixelspace/pixelspace_solarsystem....

Re:Do You Know How Much Your Computer Can Do in a Second? by nomel on Thursday June 22, 2023 @06:04PM (#36439741)
Makes you realize that space travel isn't going to happen with current physics.
Re:Do You Know How Much Your Computer Can Do in a Second? by porphyra on Thursday June 22, 2023 @06:29PM (#36440044)
The faster you go, the shorter you have to travel due to length contraction. So travelling really far distances is still possible, for example, by constant acceleration [1]. It's just that everyone you left behind will have been dead for billions of years by the time you arrive.

[1] https://en.wikipedia.org/wiki/Space_travel_under_constant_ac...

Re:Do You Know How Much Your Computer Can Do in a Second? by nomel on Thursday June 22, 2023 @08:21PM (#36441090)
> for example, by constant acceleration

Yes, this is why it won't happen, with our current understanding of physics, and the practical limitation that implies, with the resources we have. ;)

Re:Do You Know How Much Your Computer Can Do in a Second? by bitwize on Thursday June 22, 2023 @10:12PM (#36441985)
> It's just that everyone you left behind will have been dead for billions of years by the time you arrive.

sad piano plinks

https://www.youtube.com/watch?v=kEVZ3NIoEAE

Re:Do You Know How Much Your Computer Can Do in a Second? by rsaesha on Friday June 23, 2023 @03:58AM (#36444063)
To illustrate the problem of accelerating any relevant piece of mass at relativistic speeds, observe how the kinetic energy increases towards infinity as the object approaches the light speed:

https://files.mtstatic.com/site_4539/12414/0/webview?Expires...

This means it's required infinite energy to reach c speed for any mass.

And c speed is quite slow for space travel.

Just for the fun of it, let's imagine humanity has assembled, in space, an aircraft-carrier sized vessel, fully equipped to function and nurture the little humans living inside of it.

Weight: 100 ktons.

Power is infinite ok, because badly rewarded nerds discovered new physics. Good for them they are now immortals of human history.

With Lorentz kinetic energy equation, one can estimate the kinect energy this vessel would have while traveling at say, 1% of the speed of light.

Energy: 4.5*10^20 J.

This is about two thirds of the total energy Earth receives from the sun in one hour. Or close enough to the energy the world consumed in 2017.

Now we have humans inside a vessel hurdling through space at 0.01 c, in addition to the pre-existing humans in a planet swirling through space. But there is a problem! It would take 424 years to reach the nearest star system. So we need to go faster and maybe break things. Hopefully not the hull, though.

F*** it let's go 0.5 c and reach Andromeda in about 9 years - long enough to write a book.

Energy: 1.4*10^24 J.

That's 3x the energy released by the Chicxulub meteor impact. Or 30+ times the 2003 world's total fossil fuel reserves.

Which raises the question what is the fuel being used?

Doesn't matter ok because new physics, we are transforming mass literally in energy no constraints 100% efficiency lol.

By e=mc^2 that fuel would weight - at least - 14.9 ktons.

There is margin for error, since the vessel would be shedding mass, and getting lighter. That would allow engineering to run the global process at 80% efficiency, which is a very realistic metric and maybe miss a turn or two on the way to the neighboring star.

Returns not included.

Re:Do You Know How Much Your Computer Can Do in a Second? by dumdumchan on Friday June 23, 2023 @05:05AM (#36444470)
5 minutes after you takeoff you hit a pebble that obliterates your entire ship because you're covering billions of cubic meters of volume every second (in your time).
Re:Do You Know How Much Your Computer Can Do in a Second? by landryraccoon on Friday June 23, 2023 @12:23AM (#36442756)
We’ve already been to space, so it has happened with current physics.

I suppose the question is where do you want to go and how much luggage do you want to take with you?

Re:Do You Know How Much Your Computer Can Do in a Second? by idiocrat on Thursday June 22, 2023 @09:33PM (#36441707)
Re:Do You Know How Much Your Computer Can Do in a Second? by chrismorgan on Friday June 23, 2023 @03:19AM (#36443820)
I’m an Australian. A lot of the internet I interact with is in America, and a lot of the rest is in Europe. These are all hundreds of milliseconds away by fibreoptic cable, the latency of which is proportional to the speed of light.

I’ve been to America a few times. The internet is so fast there: not because of bandwidth differences, but because of latency, and especially sites carelessly loading chains of resources, which amplify the effects.

As soon as you deal in intercontinental stuff, you realise just how slow light is.

(As for studies in the effects of page load abandonment, those are never in the slightest bit relatable—at the time those studies suggest half the people are giving up, most sites still haven’t rendered anything at all, here.)

Re:Do You Know How Much Your Computer Can Do in a Second? by citrin_ru on Friday June 23, 2023 @05:37AM (#36444658)
Speed of light is the lower bound for network latency but actual internet latency also significantly affected by delays added by network equipment (routers/switches). Typically the bigger distance the more routers there are in between so this delay is also proportional to the distance. And sometimes there are almost saturated channels so there is a significant queuing delay for packets waiting to be sent. RTT AU <-> US will be higher than RTT for most pairs inside the US but RTT for the same distance within the US can vary more than 3x depending on exact network infrastructure on the way.
Re:Do You Know How Much Your Computer Can Do in a Second? by Cold_Miserable on Friday June 23, 2023 @10:24AM (#36447218)
Using fibre-optic cable where light travels in a zig-zag instead of using lasers increases latency too.
Re:Do You Know How Much Your Computer Can Do in a Second? by jebarker on Friday June 23, 2023 @10:54AM (#36447638)
I recently encountered this from both sides in my work. I was trying to get a particular single-threaded CPU program running in less than 1 microsecond. Light goes about 300m in that time. I remember reading around the same time that the Eiffel Tower is about 300m tall. So it stuck in my head that if someone switched a flashlight on at the bottom of the Eiffel Tower at the same time as my program starts the program should complete before someone at the top of the tower sees the light.