Messages in this thread | | | Date | Thu, 22 Aug 2019 06:27:17 +0200 | From | "" <> | Subject | Re: [PATCH v3 1/3] RISC-V: Issue a local tlbflush if possible. |
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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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