On Thu, Aug 23, 2018 at 9:37 AM, Christoph Hellwig <h...@infradead.org> wrote: > On Wed, Aug 22, 2018 at 08:54:51PM +0530, Anup Patel wrote: >> IMHO, rather than waiting for new CPU ON/OFF methods to come-up we >> can keep the cpu_operations ready. Also, we are not re-inventing anything >> here which we might have to discard later because cpu_operations are >> already tried and hardened for Linux ARM64. > > Which is a different cpu architecture, and has shown to actually need > it. IFF we end up needing it on riscv we can still copy and paste > it from AMD64. > > >> I agree with you that in long-term SBI-based CPU ON/OFF will be widely >> used. Most likely we will have at-least two CPU ON/OFF methods: >> 1. Existing lottery based spinning >> 2. New SBI calls > > And in this most likely case there is no need for an ops vector, > a simple if/else will be much simpler and cleaner.
Like Atish mentioned, there is a possibility of existing HW going for spin-table method instead of lottery based spinning. This means in future we will have three or more CPU ON/OFF methods: 1. Existing lottery based spinning 2. spin-table 3. New SBI calls I am fine dropping cpu_operations now but I am sure we will end-up adding it back eventually. Regards, Anup
