Raspberry Pi 3B+ and newer Unifi controller versions

September 10, 2023 8:08 PM

I'm currently running pi-hole and Unifi network controller on a Raspberry Pi 3B+ with 32-bit Raspbian (Buster). I noticed that the newly released Unifi network controller drops support for 32 bit OS's. Is upgrading to a 64 bit OS (e.g. 64-bit Bullseye) performant enough on this model, or will it be too sluggish to handle what I use it for and make me wish I had gotten a Pi 4B?

I run the pi headless and only ever log in via SSH. It sits on top of a network rack in a closet, blinking at nobody, handling all our home's DNS.

posted by rouftop to Computers & Internet (4 answers total)

I have long understood that a 64-bit processor will always be more performant running 64-bit code than it having to take the extra steps to make 32-bit code run on a 64-bit architecture. Some light googling seems to back this up, though admittedly i haven’t dabbled in 64 vs 32 in a long time. Hopefully smarter people will check in here.
posted by armoir from antproof case at 9:30 PM on September 10, 2023

It's a mixed bag in terms of performance at 32 vs 64 but, depending on workload; but your controller doesn't demand a great deal. It's not dealing with your internet traffic, it's just shepherding your access points and, if you like, guiding them to deal with your internet traffic.
I'd expect you to be fine.
posted by How much is that froggie in the window at 10:00 PM on September 10, 2023

Best answer: It might always be nicer to get a Raspberry Pi 4B, but 64-bit Bullseye does run well on a 3B+. Depending on your application, the speed difference will be somewhere between none at all to quite remarkable. In testing for work, I did find one application that was fractionally slower to start in 64-bit mode, but you're almost definitely not doing it and it only affects boot time.

There are two small downsides to 64-bit mode:

1. Higher memory use: if you're running close to memory limits on a 3B+ in 32-bit mode, you'll likely start swapping in 64-bit mode. This may be unlikely if headless and Unifi is well-behaved;
2. Heat: 64-bit mode can run considerably hotter than 32-bit. If the Raspberry Pi goes into thermal throttling (> 80 deg C) it will stay in a reduced performance mode until it is rebooted. I would be surprised if this could happen for you, unless the Unifi process runs in a hard loop. One core at 100% shouldn't cause thermal throttling in 32-bit mode, but almost certainly will in 64-bit mode.

If you can swing for another uSD card, you can keep your working 32-bit setup intact while trying an upgrade 64-bit installation
posted by scruss at 6:43 AM on September 11, 2023 [2 favorites]

having to take the extra steps to make 32-bit code run on a 64-bit architecture.
That era of Arm chip in the Pi 3B+ could be both 32-bit ARMv7 and 64-bit ARMv8 natively with the 32 processor registers in ARMv8 just not available when executing ARMv7 code. As is said elsewhere in the thread, you can have a second microSD card with the other version of the code and reboot to move between them.

The device will be adequate.
posted by k3ninho at 3:19 PM on September 11, 2023 [1 favorite]