RAM performance degradation 14.3 on RPI5

P

pkochanowski_sii

Hi,

After running the benchmarks/stream bench tool on both official FreeBSD 14.0 and 14.3 Raspberry PI 5 it seems that on the same hardware the 14.3 is consistently slower (~5-10%).
We also see this on custom ARM Cortex-A72 hardware where similar performance degradation is visible also in other scenarios (network, GELI etc.)

Does anyone know if such a degradation is expected? Were there any cache setup, memory management or other changes that could explain such behavior?
Could anyone propose some other tools that could be used in proving the issue, or profiling the memory subsystem on ARM64?

Thanks in advance,
Pawel.
 

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Power management is another possible explanation.

But generally, a 5-10% difference in stream won't show up in real applications other than maybe heavy cryptography.
 
We see it at least in case of very heavy network routing through the device (triggered with trex from outside) or with encrypted GELI partitions (so heavy crypto as you mentioned).
I would expect that any workload that needs to constantly allocate some buffers would show degradation?

Do you know if there is some way to measure the cache usage? Or ensure that the power management does not play a role here?
I have also crosschecked on amd64 virtual machines but there I could not really observe any meaningful difference using the same tool.
 
I would cross-check with a 14.3 kernel on 14.0 userland.

Did you compile stream on each platform from scratch? If yes, copy over the binary to see whether compiler differences are responsible.

I don't think we have hardware performance counters on ARM yet, but I could be wrong since I don't do heavy development on ARM.
 
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