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=-8.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no 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 C19B4C433E0 for ; Wed, 24 Jun 2020 23:37:50 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 1A38F2078E for ; Wed, 24 Jun 2020 23:37:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ghe0LNHZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1A38F2078E Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-19153-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 26028 invoked by uid 550); 24 Jun 2020 23:37:43 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 25995 invoked from network); 24 Jun 2020 23:37:42 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=mo7Dwe07kJhP63QLmOzciNFvW218NBaVIlEPp4HbWlg=; b=ghe0LNHZStIXrutzWngNn1w8HnVKxzkKAANg+f3UNbpWa1VXDLTQLRRUxQiw0ETxf1 8IwO0ripMH+IKCR86WNY+ysG11jZ8MVO51xum9mEa475UtB+fdRpajYIKrof1LeRnhfw q/KZy9ALnBT7rcr/zSWyqYTnZ3OeY5pBxENZEDhKneGeIxS3jxNDb3T6z60V1Qc+Vdy6 OTaykXWX6WKsBL92+Zu8AYSrqkunkoROSncALDdIHd5jRSMEYzkTx2v4nRNz4Z77j4S9 tRCzT7qVWnXl4XZ9bSsfQVqiYUdUQyfJWFL+rlMfK7ACBBFVz6umkgQZxUMxIfkAgDuf rFfQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=mo7Dwe07kJhP63QLmOzciNFvW218NBaVIlEPp4HbWlg=; b=avw103sWgehrDZARhdGa8gwOYOoBo2ufo5Ml7ebWOH7MNojooKkWngY4y3BtVr5bcb /sgzm0nMOF2KhHhWA7TdaCoLsY38U1EFmthMG6t+w7Odw4My+q7YWVVohVJq9pT9aWVI 05X3yKJ3HXez2UnEkiFTYajBsYQ0OIw1pdX+OASQbti4iq9xpJ0mSE8TIHFKT8ac8Pa3 vlW54QN1lV7lYimUxAwHNa8btfq5MVXQEumjMcTphd3DUHdpUlzSzUE4UfndplFBN/Yj 0T4vv6IO/16sBBkqJVuypOqAdsI7SnolvOta/t5rqbYXg9+EsJUFW2oMJ5NF4yX8Zyva Zrwg== X-Gm-Message-State: AOAM532CSqP/6wRgEXUAmFQjohHHxOlW8he/nv6dbhGISTUqbmmqHILb xMp0W4BwbK0f/DHBl6IEcrfdTw== X-Google-Smtp-Source: ABdhPJzbL+A8YRu6cQqMhEnH4JVMHPuZevDUkJdMyUg1rfNtOurVArWJG2BoYxI9g7/QXZLvtzZHnQ== X-Received: by 2002:a17:90a:9d8b:: with SMTP id k11mr267919pjp.10.1593041850610; Wed, 24 Jun 2020 16:37:30 -0700 (PDT) Date: Wed, 24 Jun 2020 16:37:24 -0700 From: Sami Tolvanen To: Peter Zijlstra Cc: Masahiro Yamada , Will Deacon , Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , Nick Desaulniers , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, x86@kernel.org, George Burgess IV Subject: Re: [PATCH 06/22] kbuild: lto: limit inlining Message-ID: <20200624233724.GA94769@google.com> References: <20200624203200.78870-1-samitolvanen@google.com> <20200624203200.78870-7-samitolvanen@google.com> <20200624212055.GU4817@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200624212055.GU4817@hirez.programming.kicks-ass.net> On Wed, Jun 24, 2020 at 11:20:55PM +0200, Peter Zijlstra wrote: > On Wed, Jun 24, 2020 at 01:31:44PM -0700, Sami Tolvanen wrote: > > This change limits function inlining across translation unit > > boundaries in order to reduce the binary size with LTO. > > > > The -import-instr-limit flag defines a size limit, as the number > > of LLVM IR instructions, for importing functions from other TUs. > > The default value is 100, and decreasing it to 5 reduces the size > > of a stripped arm64 defconfig vmlinux by 11%. > > Is that also the right number for x86? What about the effect on > performance? What did 6 do? or 4? This is the size limit we decided on for Android after testing on arm64, but the number is obviously a compromise between code size and performance. I'd be happy to benchmark this further once other concerns have been resolved. Sami