linux-kernel - Re: [PATCH 12/18] arch/tlb: Clean up simple architectures

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Date:   Mon, 15 Oct 2018 16:14:58 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Vineet Gupta <vineet.gupta1@...opsys.com>
Cc:     "will.deacon@....com" <will.deacon@....com>,
        "aneesh.kumar@...ux.vnet.ibm.com" <aneesh.kumar@...ux.vnet.ibm.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "npiggin@...il.com" <npiggin@...il.com>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux@...linux.org.uk" <linux@...linux.org.uk>,
        "heiko.carstens@...ibm.com" <heiko.carstens@...ibm.com>,
        "riel@...riel.com" <riel@...riel.com>,
        Richard Henderson <rth@...ddle.net>,
        Mark Salter <msalter@...hat.com>,
        Richard Kuo <rkuo@...eaurora.org>,
        Michal Simek <monstr@...str.eu>,
        Paul Burton <paul.burton@...s.com>,
        Greentime Hu <green.hu@...il.com>,
        Ley Foon Tan <lftan@...era.com>,
        Jonas Bonn <jonas@...thpole.se>, Helge Deller <deller@....de>,
        "David S. Miller" <davem@...emloft.net>,
        Guan Xuetao <gxt@....edu.cn>,
        Max Filippov <jcmvbkbc@...il.com>,
        arcml <linux-snps-arc@...ts.infradead.org>
Subject: Re: [PATCH 12/18] arch/tlb: Clean up simple architectures

On Fri, Oct 12, 2018 at 07:40:04PM +0000, Vineet Gupta wrote:
> Very nice. Thx for doing this.
> 
> Once you have redone this, please point me to a branch so I can give this a spin.
> I've always been interested in tracking down / optimizing the full TLB flushes -
> which ARC implements by simply moving the MMU/process to a new ASID (TLB entries
> tagged with an 8 bit value - unique per process). When I started looking into this
> , a simple ls (fork+execve) would increment the ASID by 13 which I'd optimized to
> a reasonable 4. Haven't checked that in recent times though so would be fun to
> revive that measurement.

I just pushed out the latest version to:

  git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git mm/tlb

(mandatory caution: that tree is unstable / throw-away)

I'll wait a few days to see what, if anything, comes back from 0day
before posting again.