Re: Ability to further support 32bit architectures

[Hank Barta <hbarta@gmail.com>]

On Fri, Jan 12, 2024 at 5:07 PM Alan Corey <alan01346@gmail.com> wrote:
>
> So, can you set an RPI4 to 32 bit for even more speed?
> My Pi4 config.txt (Debian Bookworm) says
>
> # Switch the CPU from ARMv7 into ARMv8 (aarch64) mode
> arm_64bit=1
>

You would have to try it to see if it is faster for your workload. I
suspect that the context switch is faster because there are fewer
registers to save/restore and they are 32 bit vs. 64 bit. Addresses
are also 32 bit, requiring less to load from RAM. (And I am not
familiar with ARM addressing modes so there may well be relative
addresses that allow shorter addresses in 64 bit mode.) I also wonder
about differences in CPU cache between 32 and 64 bit mode. Some of
these things slow specific operations while others (such as more
registers) can improve performance.

There's probably other stuff I'm not aware of that affects performance
comparisons between 64 and 32 bit mode.


-- 
Beautiful Sunny Winfield