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Admiral Grace Hopper Explains the Nanosecond

Admiral Grace Hopper Explains the Nanosecond

funbury
5 HN recommenders · discussed 2020–2025
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About this video

Admiral Grace Hopper holds up a length of wire to show how far light travels in a nanosecond, about 11.8 inches. She explains how she made the idea concrete to people who could not picture a billionth of a second.

Why it appears in the archive

HN uses it to illustrate physical latency limits and why performance and distance matter in computing.

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From the Hacker News discussion

dmoreno · 2023-01 · strong rec

My favorite is more a small presentation than an image: Admiral Grace Hoper Explains a Nanosecond. [VIDEO] For me it changed my mind on wasting time on less efficient algorithms.

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dougmwne · 2020-01 · rec

Yes it is and no it isn't. Learn from Admiral Grace Hopper: [VIDEO] The speed of light in fiber optic cable is about 2/3 the speed of light, which is why SpaceX's Starlink will have a potential latency advantage over oceanic fiber optics. It also gives good perspective on what's being thrown away when you add a single ms of latency through a router or a display. 186 miles at the speed of light. Many on HN don't get this, but this is why cloud gaming is perfectly feasible if we're running with low latency displays and inputs, low distance to the edge compute, and few routing hops.

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lozf · 2020-04 · rec

> The nanosecond wire alone should be a compelling argument. For those that haven't seen it: [VIDEO] (Of course, I expect that most here have, but xkcd 10,000 and all that.)

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klyrs · 2021-06 · rec

Speaking as somebody who never stopped optimizing like its the 90s: there's definitely a learning curve, but when microbenchmarking becomes a reflex, you learn your language in depth and the burden drops quickly. It only seems esoteric to you because the industry has collectively decided that Grace Hopper is an old codger who doesn't need to be listened to. [VIDEO]

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throw0101a · 2021-12 · rec

> Light is slow, not exactly 1 foot per nanosecond but it's a reasonable mnemonic. "Admiral Grace Hopper Explains the Nanosecond" is a good illustration of this (segment is only 2m): * [VIDEO] * [LINK] Full lecture: * [LINK]

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cogman10 · 2021-06 · reference

Pretty reminiscent of Grace Hopper's nanosecond lecture [1] Certainly there are reasons why a feature might slow down a system beyond the branching (for example, if it requires you to load other resources)... but really, the issue is that as pointed out in the youtube video. Software companies very frequently do not care about performance. [1] [VIDEO]

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BenoitEssiambre · 2022-03 · reference

I would add that software infrastructure can run incredibly fast and scale incredibly well on modern hardware if you're a bit careful about resource usage. Traditional relational DBs like Postgresql are very scalable on modern hardware. If you take the time to craft a normalized schema with low redundancy being careful about keeping data small, you can achieve performance and resource efficiency and cache efficiency hundreds of time better than bloated distributed document nosql based systems. You can also get better transactional integrity, reduce reliance on queues (use load balancers instead) and get more instant and more atomic error propagation and edge case resolution. You can really build something lean and mean to a point that would be physically impossible in distributed systems or systems that involve multiple hops over potentially congested networks (as Admiral Grace Hopper likes to remind us, distance matters in computing [VIDEO] ). As far as I know, normalized relational databases are still the best at efficiently using multiple levels of physically near caches to their full potential. Most applications don't need to scale horizontally and can easily fit on single servers (that can scale to dozens of cores and terabytes of ram). I hear arguments that it's the engineers that are expensive so it's ok to be wasteful with hardware if it saves engineering time but in my experience the type of engineers that are good at optimizations are often good at engineering in ge

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BenoitEssiambre · 2022-08 · reference

I'm glad this is becoming conventional wisdom. I used to argue this in these pages a few years ago and would get downvoted below the posts telling people to split everything into microservices separated by queues (although I suppose it's making me lose my competitive advantage when everyone else is building lean and mean infrastructure too). In my mind, reasons involve keeping transactional integrity, ACID compliance, better error propagation, avoiding the hundreds of impossible to solve roadblocks of distributed systems ( [LINK] ). But also it is about pushing the limits of what is physically possible in computing. As Admiral Grace Hopper would point out ( [VIDEO] ) doing distance over network wires involves hard latency constraints, not to mention dealing with congestions over these wires. Physical efficiency is about keeping data close to where it's processed. Monoliths can make much better use of L1, L2, L3, and ram caches than distributed systems for speedups often in the order of 100X to 1000X. Sure it's easier to throw more hardware at the problem with distributed systems but the downsides are significant so be sure you really need it. Now there is a corollary to using monoliths. Since you only have one db, that db should be treated as somewhat sacred, you want to avoid wasting resources inside it. This means being a bit more careful about how you are storing things, using the smallest data structures, normalizing when you can etc. This is not to save disk, disk is che

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