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

colin-scott.github.io

31–40 of 225 posts

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

#31
The "commodity network" thing is kind of weird. I'd expect that to make a 10x jump when switches went from Fast Ethernet to Gigabit (mid-late 2000s?) and then nothing. I certainly don't feel like they've been smoothly increasing in speed year after year.

I'm also curious about those slow 1990s SSDs.

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

#32
post #24
post #5

The slider is very bad UX : I missed it too at first. It is not pronounced enough, partly because it is all the way to the right. A former boss would say : make it red .

I sympathise that the site probably wasn’t designed with mobile in mind, but it’s impossible to go beyond 2015 without hitting the GitHub link.

You can also drag on the main view instead of the slider.

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

#34
post #21

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.

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.

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

#35
How are people practically taking advantage of the increase in speed of SSDs these days compared to network latencies? It looks like disk caches directly at the edge with hot data would be the fastest way of doing things.

I'm more familiar with the 2001-2006 era where redis-like RAM caches for really hot data made a lot of sense, but with spinning rust a disk drives, it made more sense to go over the network to a microservice that was effectively a big sharded RAM cache than to go to disk.

Seems like you could push more hot data to the very edge these days and utilize SSDs like a very large RAM cache (and how does that interact with containers)?

I guess the cost there might still be prohibitive if you have a lot of edge servers and consolidation would still be a big price win even if you take the latency hit across the network.

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

#38

How are people practically taking advantage of the increase in speed of SSDs these days compared to network latencies? It looks like disk caches directly at the edge with hot data would be the fastest way of doing things. I'm more familiar with the 2001-2006 era where redis-like RAM caches for really hot data made a lot of sense, but with spinning rust a disk drives, it made more sense to go over the network to a mic…

I don’t know, I have observed in my workloads, booting, game load, and building programs, that super fast ssds make almost no difference compared to cheap slow ssds. But any ssd is miraculous compared to a spinny drive

Presumably video editing or something might get more of a win but I don’t know.

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

#39

An instructive thing here is that a lot of stuff has not improved since ~2004 or so, and working around those things that have not improved (memory latency from ram all the way down to l1 cache really) requires fine control of memory layout and minimizing cache pollution, which is difficult to do with all of our popular garbage collected languages, even harder with languages that don't offer memory layout controls, a…

It’s interesting that L2 cache has basically been steady at 2MB/core since 2004 aswell. It hasn’t changed speed in that time, but is still an order of magnitude faster than memory across that whole timeframe. Does this suggest that the memory speed bottleneck means that there simply hasn’t been a need to increase availability of that faster cache?
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