Re: [PATCH v2 04/11] smp: replace smp_call_function_single() with smp_call()

[Peter Zijlstra]

On Fri, Apr 22, 2022 at 04:00:33PM -0400, Donghai Qiao wrote:
> Eliminated the percpu global csd_data and temporarily hook up
> to smp_call().
> 
> There is no obvious reason or evidence that the differentiation

Using the on-stack csd seems like an obvious benefit to me. Stack is
often cache-hot, while the percpu stuff is likely a cache-miss. Worse,
the call_function_data as used by the mask functions is likely a double
miss due to the O(n^2) nature of the thing.