Raspberry Pi OS 32-bit vs. 64-bit Performance

[phoronix]

Phoronix: Raspberry Pi OS 32-bit vs. 64-bit Performance

Last week marked the long awaited release of a 64-bit spin of Raspberry Pi OS. The Raspberry Pi Foundation has now made available a 64-bit build of their default Linux OS build derived from Debian for all recent Raspberry Pi hardware supporting AArch64. For those curious, here are some benchmarks looking at the performance improvement by switching from Raspberry Pi OS 32-bit to 64-bit.

https://www.phoronix.com/vr.php?view=30904

[ezst036]

How is the impact on cold-booting time? (and rebooting)

[schmidtbag]

Do 64 bit builds include more instructions? Because I wouldn't think doubling the registers would have that much of an impact on a 4GB system.

[loganj]

which SoC is capable of streaming Netflix/whatever at 4k?
anybody tried radxa zero for this?

[caligula]

Isn't rpi 4 8gb 2xhdmi nvme storage gigabit lan the goto platform for 4k?

[Jannik2099]

Do 64 bit builds include more instructions? Because I wouldn't think doubling the registers would have that much of an impact on a 4GB system.

Some instructions have been added to fill out shortcomings, and most importantly the floating point (and vector) instructions have been reworked to be significantly less of a fuckup

Though an extra 16 registers surely helps too

[royce]

How about memory consumption though? I would expect 64 bit to be worse for obvious reasons, which can be important on devices with such limited resources. Especially the Zero with its half gig of RAM.

[birdie]

I remember at least on x86 some tests were faster in 32bit vs 64bit mode in the past - looks like ARM64 is unequivocally and distinctly faster, as all the software and compilers have learned to utilize 64bit instructions.

How about memory consumption though? I would expect 64 bit to be worse for obvious reasons, which can be important on devices with such limited resources. Especially the Zero with its half gig of RAM.

How so if it completes the same work faster? The only thing that goes for 32bit is a more modest memory consumption.

[coder]

Do 64 bit builds include more instructions? Because I wouldn't think doubling the registers would have that much of an impact on a 4GB system.

As noted, vector math was significantly improved (64-bit -> 128-bit).

Also, according to the AArch64 wikipedia page:

Instructions are still 32 bits long and mostly the same as A32 (with LDM/STM instructions and most conditional execution dropped).

• Has paired loads/stores (in place of LDM/STM).
• No predication for most instructions (except branches).

I'd have expected predication to be a win, but the fact they removed it says otherwise.

[kozman]

Wow, these numbers are eye opening and prove there was more perf to squeeze out of the lowly 64-bit capable Pi by simply going 64-bit OS. No shock to me though.

So basically those that said the equivalent of "moving the Pi to 64-bit wouldn't do shit" were not only very wrong but proves they were moron of the highest order. "That's why I looooooooooove....Nestle Crunch. <SNAP><Insert morons of the highest order being snatched away screaming>." pretty much sums up my feelings on the matter.

Now that kernel 5.15 is in play via rpiupdate, it should squeeze out even further gains for at least the Pi4 users.