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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 16C6DC43387 for ; Thu, 3 Jan 2019 23:56:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D378D20660 for ; Thu, 3 Jan 2019 23:56:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Xb1fxhBm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728978AbfACX4i (ORCPT ); Thu, 3 Jan 2019 18:56:38 -0500 Received: from mail-pl1-f196.google.com ([209.85.214.196]:38299 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725940AbfACX4i (ORCPT ); Thu, 3 Jan 2019 18:56:38 -0500 Received: by mail-pl1-f196.google.com with SMTP id e5so16568040plb.5 for ; Thu, 03 Jan 2019 15:56:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=7SwYmZ0oIMjQE0KO/pvJoJQbV+s3sCOCab+M0pUSV+E=; b=Xb1fxhBmr8pS37BigirB+qdUxUCqbCGQpbwHq9PV7ubJ48/6rGamw5jeDKE/mt875U CuKrB4O0Ue4wE/V93ClD515mkfk7ZrVnz8S162CFf13dcjlWtn2pMv/UXcZLLAuGtBu0 XZqTwL12MdM49hD5yIkz+B83+IiaANCkNH30ERDtPwFIuEMk9fsf19Hv2a8C0aD014x7 2qmiSyWQ7+SCtslU9/aF7voxXgs3cHeGZKqdzYv/K8OR9lEU6OWkspuT43Ia4bnZYeOh k/v2Ldk6EfTqwUcD1pxPqrO8663nIn0iTIlXTmgi2qnqAHOcBVpcInvbyfbkK/e+hh+f 7Vsw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=7SwYmZ0oIMjQE0KO/pvJoJQbV+s3sCOCab+M0pUSV+E=; b=VQA+ebFOLnIWKbhOfaEC50RC7JKXx6+xWM3HnilEx1lMszXD/zR2HtweOnxnw0hpBf 6zxJyjDKzXVIhUOZZw2iJ8QDbhKXwwXxXOkW7OIFg7o5UhCgJZ6Q81DLdxAd5aAEPaMB 4/8343Ec8TOeIdCw31z++QVw3IOtRU17VX1p9+gka8pOQzqk9aESM/+27K/PcGGiRLzK rh8ldykpSPtPurNqYrKRnG0IfBYOp8hLRGk41P3alWuFNCq5ecNyYwD3LEV3V17Xix6T BnIIFA3tVFDxmOz2yC6xnRinQTqkjNasKmBkr1N/BMWDIDWij8+ZZfQh31+ljb6ZAAAC tDYQ== X-Gm-Message-State: AJcUukcqFCiuNGhk85pMQi0TdxtOBDIRUJSptrbFMbeBR6jKVHVlkG5Y kX3lxh3B3uJ3gG5/VoNZenM= X-Google-Smtp-Source: ALg8bN5+MPPkKOGc6W2cfNO6C2hGiJe0VNsSjdcP+ZzmuqATwtUEll8ZYRRv1VtpNkwlr62ak64ncg== X-Received: by 2002:a17:902:d202:: with SMTP id t2mr49596654ply.193.1546559797382; Thu, 03 Jan 2019 15:56:37 -0800 (PST) Received: from [10.2.13.140] ([208.91.2.1]) by smtp.gmail.com with ESMTPSA id o189sm92893924pfg.117.2019.01.03.15.56.35 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 03 Jan 2019 15:56:36 -0800 (PST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 12.2 \(3445.102.3\)) Subject: Re: [RFC v2 1/6] x86: introduce kernel restartable sequence From: Nadav Amit In-Reply-To: <20190103234029.GH6118@tassilo.jf.intel.com> Date: Thu, 3 Jan 2019 15:56:34 -0800 Cc: Ingo Molnar , Andy Lutomirski , Peter Zijlstra , Josh Poimboeuf , Edward Cree , Thomas Gleixner , LKML , X86 ML , Paolo Abeni , Borislav Petkov , David Woodhouse Content-Transfer-Encoding: quoted-printable Message-Id: References: <20181231072112.21051-1-namit@vmware.com> <20181231072112.21051-2-namit@vmware.com> <87va35e61a.fsf@linux.intel.com> <263A441C-F062-491F-9E95-F00FA2092A99@gmail.com> <20190103224835.GG6118@tassilo.jf.intel.com> <28F28C02-1817-4A0A-B488-216FDF22169A@gmail.com> <20190103234029.GH6118@tassilo.jf.intel.com> To: Andi Kleen X-Mailer: Apple Mail (2.3445.102.3) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Jan 3, 2019, at 3:40 PM, Andi Kleen wrote: >=20 >> Thanks for the explanations. I don=E2=80=99t think it would work = (e.g., IRQs). I can >> avoid generalizing and just detect the "magic sequence=E2=80=9D of = the code, but let >> me give it some more thought. >=20 > If you ask me I would just use compiler profile feedback or autofdo = (if your > compiler has a working version) >=20 > The compiler can do a much better job at optimizing this than you ever = could. >=20 > Manual FDO needs some kernel patching though. As long as you are willing to profile and build your own kernels. = (Profiling will not tell you if users are about to use IPv4/6). I also don=E2=80=99t see how FDO can support modules.