From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ECC02C28CF6 for ; Fri, 3 Aug 2018 17:39:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A7FE121784 for ; Fri, 3 Aug 2018 17:39:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A7FE121784 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=surriel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727819AbeHCThK (ORCPT ); Fri, 3 Aug 2018 15:37:10 -0400 Received: from shelob.surriel.com ([96.67.55.147]:44340 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727171AbeHCThK (ORCPT ); Fri, 3 Aug 2018 15:37:10 -0400 Received: from imladris.surriel.com ([96.67.55.152]) by shelob.surriel.com with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1fle3M-0000vD-Eq; Fri, 03 Aug 2018 13:39:52 -0400 Message-ID: <1533317992.28585.103.camel@surriel.com> Subject: Re: [PATCH 11/11] mm,sched: conditionally skip lazy TLB mm refcounting From: Rik van Riel To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, luto@kernel.org, x86@kernel.org, efault@gmx.de, dave.hansen@intel.com Date: Fri, 03 Aug 2018 13:39:52 -0400 In-Reply-To: <20180803172516.GM2458@hirez.programming.kicks-ass.net> References: <20180801100255.4278-1-riel@surriel.com> <20180801100255.4278-12-riel@surriel.com> <20180803155618.GB2494@hirez.programming.kicks-ass.net> <1533314448.28585.101.camel@surriel.com> <20180803172516.GM2458@hirez.programming.kicks-ass.net> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-zzrHFJ9L2f/2GqQONPoP" X-Mailer: Evolution 3.26.6 (3.26.6-1.fc27) Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-zzrHFJ9L2f/2GqQONPoP Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, 2018-08-03 at 19:25 +0200, Peter Zijlstra wrote: > On Fri, Aug 03, 2018 at 12:40:48PM -0400, Rik van Riel wrote: > > On Fri, 2018-08-03 at 17:56 +0200, Peter Zijlstra wrote: > > >=20 > > > Why can't we skip the ->active_mm swizzle and keep ->active_mm =3D=3D > > > ->mm. > > >=20 > > > Doing the swizzle but not the refcount just makes me itch. > >=20 > > I am working on that now, it adds another 7-8 > > patches on top of this series. >=20 > I thought those were taking ->active_mm out entirely, not avoiding > the > swizzle, but I might have missed something in the middle :-) At this point, only the fact that ->active_mm is still being used by a few places in the code :) > > The big question is, do we want this optimization > > to wait for further cleanups, or should we run with > > code that seems to be stable right now, and put > > additional cleanups and enhancements on top of it > > later? >=20 > At the very least the Changelog needs to explain why we cannot do > away > with the swizzle now and how doing the swizzle without the > refcounting > is not completely broken (I think I see, but urgh). The changelog for patches 9 & 10 explains, I think. What is missing from my explanation? How would you like to see it explained? --=20 All Rights Reversed. --=-zzrHFJ9L2f/2GqQONPoP Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEEKR73pCCtJ5Xj3yADznnekoTE3oMFAltkk2gACgkQznnekoTE 3oPD5Qf+MiuWUhnghz5Q5O4mfa+kl4ThWgPH5dQpaxpXfs4nvc63I0f7IaWeILa/ d1goI2hZbn2rlawcBw8oFkGgiLneKZYgifhWSokFfGJXqwEKXWeMYThJi8zx2Qej CIu17Yr6fwPFYKqwrSvEGmaFHseOLt+sD7KCbsI9Yz56xnCC7pqsrmH3DYqw6EYh dCFblk/35+1Iud6z5y+aFztf4Y117gn3NgFrpLmGlzEB0aMGk/eW48rF5qfDNPz9 3vkxl6wvco80nU+qbKnKLXrZ0GNAiXY4x2OUGoRe6kyAlDNBKAgEzb34obXwh8iR U7YCvVehTqqbSqshy9aW5eeX/YBhlg== =FuK3 -----END PGP SIGNATURE----- --=-zzrHFJ9L2f/2GqQONPoP--