Messages in this thread | | | From | Andy Lutomirski <> | Date | Mon, 9 Oct 2017 11:31:46 -0700 | Subject | Re: [RFC PATCH] x86/mm: Flush more aggressively in lazy TLB mode |
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On Mon, Oct 9, 2017 at 11:08 AM, Borislav Petkov <bp@alien8.de> wrote: > On Mon, Oct 09, 2017 at 10:50:34AM -0700, Andy Lutomirski wrote: >> The choices are somewhat lazy and not lazy at all. > > Yeah, you probably should explain those choices somewhere and what > exactly they mean. > >> The degree of simplification I would get by removing it is basically >> nil. The debugfs code itself goes away, and a >> static_branch_unlikely() turns into a static_cpu_has(), and that's it. > > Sure. But it is one variable less which is not really needed by the > widest audience. > >> The real reason I added it is because Chris Mason volunteered to >> benchmark it, and I'll send it to him once it survives a bit of >> review. > > Sure but it still doesn't need to be upstream. You can do all the > measurements with a patch ontop. You don't need the permanent knob in > debugfs either. After a year, no one would really need that anymore, > since the majority will be PCID machines. > >> This is non-lazy. It's roughtly what our state was in old kernels >> when we went lazy and then called leave_mm(). > > non-lazy when we went lazy?! > > Now I'm confused :)
The function enter_lazy_tlb() is horribly named. It really just means scheduler_doesnt_need_an_mm_anymore().
--Andy
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