tokio: fix cache line size for RISC-V #5994
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Currently tokio uses cache line size data from Go, which is not sufficient at least for T-Head C910 cores. The RISC-V Profiles document defines a maximum 64 bytes cache line for RVA22U64 (although the maximum is 128 bytes for RVA20U64), and the Linux kernel currently assumes 64B cache line too. Change the cache line size used to 64 bytes to match Linux and RVA22U64. Signed-off-by: Icenowy Zheng <[email protected]>
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Motivation
When reading the tokio source code, I realized it currently uses 32B cache line size for RISC-V, which seems to be not sufficient. (Go uses 32B too, but it's currently known to be too small, see [1])
[1] https://go-review.googlesource.com/c/go/+/526659
Solution
Removing all set cache line size of 32B for riscv*, and add reference from kernel that uses 64B cache line size.