linux-kernel - Re: [PATCH v3 4/9] x86/mm/tlb: Flush remote and local TLBs concurrently

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Message-ID: <20190722193251.GF6698@worktop.programming.kicks-ass.net>
Date:   Mon, 22 Jul 2019 21:32:51 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Nadav Amit <namit@...are.com>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        the arch/x86 maintainers <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Sasha Levin <sashal@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        Juergen Gross <jgross@...e.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>
Subject: Re: [PATCH v3 4/9] x86/mm/tlb: Flush remote and local TLBs
 concurrently

On Mon, Jul 22, 2019 at 07:27:09PM +0000, Nadav Amit wrote:
> > On Jul 22, 2019, at 12:14 PM, Peter Zijlstra <peterz@...radead.org> wrote:

> > But then we can still do something like the below, which doesn't change
> > things and still gets rid of that dual function crud, simplifying
> > smp_call_function_many again.

> Nice! I will add it on top, if you don’t mind (instead squashing it).

Not at all.

> The original decision to have local/remote functions was mostly to provide
> the generality.
> 
> I would change the last argument of __smp_call_function_many() from “wait”
> to “flags” that would indicate whether to run the function locally, since I
> don’t want to change the semantics of smp_call_function_many() and decide
> whether to run the function locally purely based on the mask. Let me know if
> you disagree.

Agreed.