On Fri, Aug 04, 2023 at 10:17:35AM -0400, Guo Ren wrote:

quoted

See, this is where the ARM64 WFE would come in handy; I don't suppose
RISC-V has anything like that?

Em... arm64 smp_cond_load only could save power consumption or release
the pipeline resources of an SMT processor. When (Node1 cpu64) is in
the WFE state, it still needs (Node0 cpu1) to write the value to give
a cross-NUMA signal. So I didn't see what WFE related to reducing
cross-Numa transactions, or I missed something. Sorry

The benefit is that WFE significantly reduces the memory traffic. Since
it 'suspends' the core and waits for a write-notification instead of
busy polling the memory location you get a ton less loads.


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