RPI 4, 2G and RPI Zero W projects

[fox]

I sold my Pi 3B today, and am looking to buy the 4 with 4 gb memory. I read a few reviews suggesting that 8 gb is excessive if you don't do a lot of multitasking or working with large graphic files. I'm debating between buying a make-it yourself kit from BuyaPi, or a Labists kit that is on sale at Amazon for $115. I would prefer to buy from BuyaPi (Ottawa-based), but the Labists kit is on sale and includes a few items you don't get from a comparable BuyaPi "kit". The labist case is also one of the nicer ones I've seen; attractive with good ventilation and space for attachment boards; you can see it here. I'm going to buy tonight, so if anyone has any thoughts on what I should buy, please post.

[ssfc72]

Thanks for the info Mike.  A very good sale price.

[fox]

I have my 4 now, and have just set it up with BerryBoot, booting from an old SSD. (Actually, it still requires the SD card to start up, but it directs the system to boot from the SSD.) Using 64 bit Raspberry Pi OS, this seems quite responsive so far; much more so than the Pi 3B. I would consider this quite usable as a desktop, assuming that the software I need is available. I'll be exploring that in the next few days.

[Jason Wallwork]

But the most important question: did you get the one with 4 GB or 8 GB of memory?

I've read somewhere that if programs are compiled with 64-bit support, they will run ~30% faster. But they may just apply to PCs. The OS is obviously the platform on which everything else is based so having been compiled for the 64-bit processor should make a fair bit of difference. The RPi 3 has a 64-bit processor but the OS isn't as I'm sure you already know. And I don't think you can run 64-bit programs without a 64-bit OS but I don't know how many programs on the RPi have been built with 64-bit support. IOW, the increased performance depends on the software taking advantage of it. But the one thing you did get, regardless, is the ability to access more than 4 GB of RAM, a 32-bit limitation.

[fox]

I didn't install the 64-bit version on purpose; when I booted up BerryBoot that version is what showed as available. I got the 4 gb RPi4.

[Jason Wallwork]

I didn't install the 64-bit version on purpose; when I booted up BerryBoot that version is what showed as available. I got the 4 gb RPi4.

The 32-bit version would probably run but I doubt there'd be any benefit to doing so with a 64-bit processor. So that makes sense.

[gmiller1977]

32bit on 64bit doesn't have any performance increases.  If recompiled, properly, 64bit binaries will typically offer a performance increase of what Jason indicates.

[Jason Wallwork]

Recently I read (and can't find) an article that said there might be a situation in which running a 32-bit OS (and 32-bit programs) on a 64-bit OS would be preferable - if your system has 2 GB RAM or less. 64-bit processors can access more RAM (> 4 GB) which is great but that comes with a bit of memory hit.

Everything running (as well as programs/data that is cached) is some space in RAM. Programs have to know how to access that RAM so each chunk of data has a starting address. That'd be like addresses on a street with the data being the people and things in them. But you also need to know where to find that data. That'd be like a phonebook. You need to find someone, it tells you where they are (or should be during a pandemic).

A 64-bit OS can not only store longer addresses it has to even if the address wouldn't normally need the space. Think of a phonebook that used to have 4 columns but now some people live at 8938493893493489 Lundy's Lane and they have names like John Iljieafiejliaifejeoigiggmmg instead of John Smith, so the phonebook can only have 2 columns now. There are lots of shorter names and shorter addresses but that doesn't matter. They all need that larger space now. The phonebook has doubled in size even if only 20% of those addresses actually need double the amount of space. Of course, that's assuming the same font size. But for the analogy, it would have to, because we can't make bits in a computer take up less room. So just like we need more pages in the phonebook, we need more RAM now just to store those addresses.

Someone told me years ago that if you're using 8 GB of RAM, 1 GB alone is used to store the addresses (assuming you're using nearly all of the RAM). That's no big deal on systems with lots of RAM. But if you only have a system with 1 GB of RAM, you don't want to give up 125 MB just for storing addresses that you don't actually need. So a 32-bit OS (which means 32-bit programs, too) is better for such a system. This might be why the Raspberry Pi 3 (and I believe the previous models) used a 32-bit OS even though it was capable of running a 64-bit one. With Pi 4, you have at least 4 GB of RAM so you can afford to use that extra RAM.