On Wed, 26 Oct 2022, Wen Yao wrote: > This patch use riscv AMO(Atomic Memory Operation) instructions to > optimise some this_cpu_and this_cpu_or this_cpu_add operations. > It reuse cmpxchg_local() to impletment this_cpu_cmpxchg macros. > It reuse xchg_relaxed() to impletment this_cpu_xchg macros. Are you sure that these changes gives you any benefit vs disabling preempt or irq offs? I dont know too much about atomics on riscv but it looks like you are using full atomics. The performance penalty for the use of those is usually drastic. Often irq/preempt off is better. Could you run some of the synthetic tests to establish the benefit? F.e. run the synthetic tests for the slub allcator with and without these patches. > + __asm__ __volatile__( \ > + "amo" #asm_op ".w" \ amo = atomic operation?
