"What if a programming language would provide us with a structure that would act like an array of structs, but internally it would really behave like a struct of arrays?"
What about SQL when using a columnar data store?
The compiler will optimize that away
251–260 of 329 posts
Re: The compiler will optimize that away
#252"What if a programming language would provide us with a structure that would act like an array of structs, but internally it would really behave like a struct of arrays?" What about SQL when using a columnar data store?
An array of structs is already a struct of arrays if you're willing to do some offset math.
Re: The compiler will optimize that away
#253The implicit premise of the article seems to be that all software has to be heavily optimized. This is completely wrong. All the languages mentioned in the article are still around because it doesn’t matter how performant 99% of code is. For the 1%, we can think about cache misses, SIMD and data parallel approaches. In my experience this is totally possible and not too hard, but has the enormous downside of making th…
This is exactly how we ended up with someone charging you $50/month to run a browser on a supercomputer.
Re: The compiler will optimize that away
#254The implicit premise of the article seems to be that all software has to be heavily optimized. This is completely wrong. All the languages mentioned in the article are still around because it doesn’t matter how performant 99% of code is. For the 1%, we can think about cache misses, SIMD and data parallel approaches. In my experience this is totally possible and not too hard, but has the enormous downside of making th…
> All the languages mentioned in the article are still around because it doesn’t matter how performant 99% of code is.
It’s worth challenging this assumption and asking whether it’s really true, or whether this belief is old and outdated like the old languages. I’m certain that providers of compute infrastructure like Amazon, Microsoft, Google and others completely disagree that performance doesn’t matter. Letting slow code run literally costs them money because it prevents multiple people from being able to use the same hardware resource. Even on your own machine, slow processes hog resources that other processes could use. The reason my laptop fans keep spinning up in Windows while my machine is basically idle is due to hundreds of processes written by people who erroneously believe the performance of 99% of the code doesn’t matter. We’re also at a point where we’ve started to measure the energy efficiency and environmental impact of wasting compute cycles. So, performance always matters.
> For the 1%, we can think about cache misses [...] but that has the enormous downside of making code hard to reason about.
You’re agreeing with the author here. Maybe you missed the explicit point in the in the article that is calling for a language that makes basic cache awareness a first class citizen, precisely so that it’s easier to reason about?
“This is exactly the type of problem that should be solved via the features of our programming languages, since writing these custom sorting functions is very tedious. What if a programming language would provide us with a structure that would act like an array of structs, but internally it would really behave like a struct of arrays? We could program in the typical object oriented way that is convenient for humans, while still enjoying in great performance due to playing nice with the hardware.”
> You are also optimizing for today’s hardware, which means that it might not run that great on new hardware in 20 years.
For the last 20 years, the need to be cache-aware has increased in importance. For the next 20 years, the gap between memory and compute will get larger still. There’s no scenario on the horizon where we don’t have to become more memory conscious as programmers or use more memory conscious languages and tools. There aren’t many performance tricks and concepts that worked 20 years ago and don’t work today. Using a structure of arrays (SoA) instead of an array of structures (AoS) has long been and will continue to be a good idea.
Re: The compiler will optimize that away
#255Earlier quoted context omitted.
This attitude is very common and has clearly degraded software development particularly for users, and like most issues afflicting modern software it's not perceived by developers so it "doesn't exist" to them. As the top reply to this mentioned, anyone can easily tell how much slower software is today even when computers and devices are so fast now! All in the name of "making code easy to reason about." I have news…
I think other users in here are more on the right track about where the blame for this lies. As you alluded to, a lot of programmers are happy to tweak and refine for ages so it's probably not that. Is it just that programmers are lazy or need to care more or be better educated about optimization? Honestly I really doubt it. I fully agree with the other takes that companies have incentives to ship working software qu…
You're probably right honestly that bean counters are mostly to blame. I will say the attitude of being afraid of difficult code is a problem in modern IT (IT of any generation really) and doesn't help but companies not caring about users being the primary cause of bad, unperformat code is the correct take. Conversely then, the handwaving of the OP comment is wrong too, so if we limit the discussion of what one ought to do, I still stand by my point.
Re: The compiler will optimize that away
#256Earlier quoted context omitted.
> Why are all my dev tools super slow? If my time is important, Quantify important into how much you spend on your tooling. Aside from some key bits of development software at the IC / board layout, almost everything a software developer needs is free, open source or cheap. Noone pays $1000 for an IDE anymore.
> Noone pays $1000 for an IDE anymore. How many minutes per developer per day before that level of expenditure pays for itself inside 2-3 months? Who cares? The premise is false, you can't buy it. There is no "fast tools" you pay for. Every decent shop got their devs an SSD at the first available opportunity because it paid for itself really quickly, cost you money _not_ to buy them. The very definition of a false ec…
I don't have a hard math here. But here's some example: JRebel. It allows for instant class reloading in JVM. It increases one's productivity tremendously. And it's expensive as hell. They used to have free version, they don't have it anymore. I can only judge that they're struggling and forced to squeeze all they can, because developers will prefer free restricted version over paid full-featured version. I know, I do, I don't value my own time and I'll never pay more than $100/year for a tool (and hopefully much less), I already trying hard to justify Idea subscription, because it seems that Idea CE contains almost everything I need.
If developers would love to spend thousands of bucks here and there, paid developer tools industry would flourish. But I think that it's even degraded compared to the past. I remember paid Delphi IDE and I remember paid components and that was a thing back then. I can't remember any popular paid React component right now, despite the fact that much more people are using React compared to Delphi.
Re: The compiler will optimize that away
#257Earlier quoted context omitted.
That is both not true and not what you said at first. Transistor density has continued to rise but there is only so much you can do when people mostly run javascript on a single thread. There were a lot more break throughs in the early days of electronic components too because everything was new. CPUs are a world away from where they were two decades ago, but people don't notice because typing into a facebook window…
If you only have a single core (common on battery powered devices) then you should only run a single thread. Excess parallelism doesn't make things go faster and uses more memory. The important thing is avoiding unnecessary waits on non-CPU resources like I/O.
This reads like a reply to a different comment. The person above was saying there haven't been any advancements in CPUs or GPUs which is obviously not true. No one said anything about battery powered devices and even those have had multiple cores for many years now - as a result of transistors still shrinking.
Re: The compiler will optimize that away
#258"What if a programming language would provide us with a structure that would act like an array of structs, but internally it would really behave like a struct of arrays?" What about SQL when using a columnar data store?
An array of structs is already a struct of arrays if you're willing to do some offset math.
That would make the whole thing moot. The crucial difference between AOS and SOA is that the "physical" memory layout is different:
AOS: [xyzw][xyzw][xyzw][xyzw]
vs
SOA: [xxxx][yyyy][zzzz][wwww]
If you have such a layout, a SIMD instruction touching 4 packed words has quite different behavior. Arguably, SIMD is pointless without SOA or AOSOA.
Re: The compiler will optimize that away
#259Earlier quoted context omitted.
This attitude is very common and has clearly degraded software development particularly for users, and like most issues afflicting modern software it's not perceived by developers so it "doesn't exist" to them. As the top reply to this mentioned, anyone can easily tell how much slower software is today even when computers and devices are so fast now! All in the name of "making code easy to reason about." I have news…
>As the top reply to this mentioned, anyone can easily tell how much slower software is today even when computers and devices are so fast now! All in the name of "making code easy to reason about." Yeah - it also doesn't crash my PC when an app segfaults, hell even video driver failing these days won't bring my system down. I don't need to restart my PC when I plug in a device. That's not really compatible with your…
My point really isn't about luddite vs. anti-luddite, I'm talking about performance and how it affects users. Also, you're right that less performant or less elegant tools win out sometimes (like the good old mac vs windows debates before macos and apple in general made a come back) and that is due to a variety of reasons. That's fine, life is complicated and many factors affect who wins in life, it doesn't mean we can't still ask for better things though.
Still I don't know what bearing of all this has on the point I made above.
Re: The compiler will optimize that away
#260Back in the real world the best code is code that ships.
Occasionally I find myself doing something stupid ( if you use Unity and try to do advance distance calculation in Update your going to have a bad time ) , but usually I never have to optimize. Modern computers might as well be magic