Does PRFM L3 prefetch to SLC or is treated as NOP?

Q&A
1

From Ampere Altra Datasheet (https://amperecomputing.com/assets/Altra_Rev_A1_DS_v1_50_20240130_3375c3dec5_1c5d4604fa.pdf), there is no L3 but a SLC(System Level Cache). So what is the effect of using PRFM L3 ? Is it a NOP or will prefetch to SLC ?

2

I’m afraid I don’t know the answer to your question, I imagine that you are right that PRFM(L3) is a noop, and PRFM (SLC) prefetches to SLC. At least that’s my interpretation from reading the Arm docs for PRFM.

https://developer.arm.com/documentation/ddi0602/2024-03/Base-Instructions/PRFM--register---Prefetch-Memory--register--?lang=en