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SubjectRe: [PATCH v3 1/3] RISC-V: Issue a local tlbflush if possible.
On Thu, Aug 22, 2019 at 04:01:24AM +0000, Atish Patra wrote:
> The downside of this is that for every !cmask case in true SMP (more
> common probably) it will execute 2 extra cpumask instructions. As
> tlbflush path is in performance critical path, I think we should favor
> more common case (SMP with more than 1 core).

Actually, looking at both the current mainline code, and the code from my
cleanups tree I don't think remote_sfence_vma / __sbi_tlb_flush_range
can ever be called with NULL cpumask, as we always have a valid mm.

So this is a bit of a moot point, and we can drop andling that case
entirely. With that we can also use a simple if / else for the local
cpu only vs remote case. Btw, what was the reason you didn't like
using cpumask_any_but like x86, which should be more efficient than
cpumask_test_cpu + hweigt?

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