linux-kernel - Re: [PATCH 5/9] x86/mm/tlb: Optimize local TLB flushes

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Message-ID: <CALCETrXbC=w5KyR8x-hD24DC0BzZ3MjHR1FUOoEXkBOPHPXwXQ@mail.gmail.com>
Date:   Wed, 26 Jun 2019 09:33:32 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Nadav Amit <namit@...are.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        X86 ML <x86@...nel.org>, Thomas Gleixner <tglx@...utronix.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH 5/9] x86/mm/tlb: Optimize local TLB flushes

On Tue, Jun 25, 2019 at 2:36 PM Dave Hansen <dave.hansen@...el.com> wrote:
>
> On 6/12/19 11:48 PM, Nadav Amit wrote:
> > While the updated smp infrastructure is capable of running a function on
> > a single local core, it is not optimized for this case.
>
> OK, so flush_tlb_multi() is optimized for flushing local+remote at the
> same time and is also (near?) the most optimal way to flush remote-only.
>  But, it's not as optimized at doing local-only flushes.  But,
> flush_tlb_on_cpus() *is* optimized for local-only flushes.

Can we stick the optimization into flush_tlb_multi() in the interest
of keeping this stuff readable?

Also, would this series be easier to understand if there was a patch
to just remove the UV optimization before making other changes?

--Andy