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Comment by sillysaurusx | Hacker News Reader

I see you mentioned running an OS off a ramdisk. I recommend this, just to see how incredibly fast it can be.

And also how incredibly not-fast. The fact is that most applications are memory bandwidth bound, once you eliminate the disk as a bottleneck. Not CPU bound. So when you run off a ramdisk, it's not actually helping as much as I thought it would.

But! One really neat thing you can do is to save VM checkpoints, so that backing up your computer is as simple as checkpointing the VM. So there are other advantages.

Doing some video editing is fun too, and 3D modeling. Ever want to dabble with ZBrush? Now's your chance. Get yourself a nice big monitor and Wacom tablet. Yum.

(And then, y'know, set the hobby down and never touch it again, just like the rest of us. But it's fun while it lasts.)

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Hey sillysaurus, thanks for the ideas. Incidentally i did recently go on a little Procreate drawing kick so Zbrush sounds perfect. BTW i really appreciate your writing and community building online.

Can you please describe an example of where an application might be memory bandwidth bound, and what engineering techniques might be used to circumvent this restriction?

In modern times, it's hard to describe an example where an application isn't memory bandwidth bound. It's basically the primary bottleneck.

Most programs spend little time doing computation, or reading I/O. Everyone knows I/O is expensive, so it's minimized.

But there's no getting around the fact that every time you want to do anything at all, you have to shuffle around memory. There's no choice.

One way to circumvent this restriction is to make memory faster. This is difficult with traditional approaches.

I was going to point to Memristors as a possible way forward, but honestly I don't know enough about the subject.

We're getting to the point where we're speed-of-light bound, I believe. I.e. running up against fundamental limits.

Still, there's a lot of room. One interesting thing is to read Feynman's lectures on computation: https://theswissbay.ch/pdf/Gentoomen%20Library/Extra/Richard...

He points out that a reversible computer is actually the most efficient, from an energy perspective. But the tradeoff is that things take more time. If you want to take less time, it generates more heat. And more heat means inevitable delay.

Check the first chart:

https://www.forrestthewoods.com/blog/memory-bandwidth-napkin...

This is the kind of blog post that just ignites a passion for serious software engineering.

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