linux-kernel - Re: [patch 55/60] x86/mm: Use INVPCID for __native_flush_tlb

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Date:   Tue, 5 Dec 2017 15:08:50 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>, X86 ML <x86@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Borislav Petkov <bpetkov@...e.de>,
        Greg KH <gregkh@...uxfoundation.org>,
        Kees Cook <keescook@...gle.com>,
        Hugh Dickins <hughd@...gle.com>,
        Brian Gerst <brgerst@...il.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Denys Vlasenko <dvlasenk@...hat.com>,
        Rik van Riel <riel@...hat.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        David Laight <David.Laight@...lab.com>,
        Eduardo Valentin <eduval@...zon.com>, aliguori@...zon.com,
        Will Deacon <will.deacon@....com>,
        Daniel Gruss <daniel.gruss@...k.tugraz.at>,
        Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [patch 55/60] x86/mm: Use INVPCID for __native_flush_tlb_single()

On Tue, Dec 05, 2017 at 05:51:28AM -0800, Dave Hansen wrote:
> On 12/04/2017 02:51 PM, Peter Zijlstra wrote:
> > We should find some of the benchmarks that were used to determine
> > tlb_single_page_flush_ceiling and measure. I've not gotten around to
> > doing either.
> > 
> > Someone called Dave Hansen did that patch and might still have something
> > lying around to help with that:
> > 
> >   a5102476a24b ("x86/mm: Set TLB flush tunable to sane value (33)")
> 
> I hate git. :)

:-)

> But, yeah, we have certainly changed enough variables to necessitate
> measuring it again.

Its more than that, I think much of that could show if it makes sense to
use invpcid_flush_one() at all.