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Thu, 28 Jan 2021 16:20:19 -0500 Received: from mail-io1-xd2e.google.com (mail-io1-xd2e.google.com [IPv6:2607:f8b0:4864:20::d2e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 998CAC061574; Thu, 28 Jan 2021 13:19:39 -0800 (PST) Received: by mail-io1-xd2e.google.com with SMTP id u8so2023964ior.13; Thu, 28 Jan 2021 13:19:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:reply-to:from:date:message-id :subject:to:cc; bh=8KacIPQbORj40QvqegzfTEzGvNMpxCBDGW80/SheMdk=; b=uALI5RA+UDVO9yHlHg1R3fl2m3imATTzEiriaqP3VfyeMAPL2iBha5KO2Iw1Mc9cAO qrmOEjZpf9KwUgQl6Ai7NYp4T5fmBhzII0hJMq6pwcM7rX3tb0v3PWO+cpdDONkxKcAo B5C7W4AcZx7t8ffBYZ1a48Uv2IvkYKNE+TqKs6T/yyFx3TLy6Fr3qbwnE2zGd78z23Ch iuTpYHzM8MXi3VGAKZwSSAJroXHRihgTI7hZw3NFpP3sBAFA2kVXPgviPvrq3yNR9Z60 /xmBDLlwbCOxBOoibx/AVqO85LStXaIcbl0MKtP8dp+IzLr/zNU/BpvZ0GZPR7Ju7XkO UOKQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:reply-to :from:date:message-id:subject:to:cc; bh=8KacIPQbORj40QvqegzfTEzGvNMpxCBDGW80/SheMdk=; b=nkcFpnKJBH1D3OZ8WGQnjl/o7Xw19YRhoS3Po+AnOpWZCh/Ki8V94aL2VIFvP8QBoY FkelOmbV1Kl7RX65YkQh5SeRqgtfc8UGWlwY4r+Sfg7MEXbWvJy1NtllzDl5zMSL3750 68UBG4sWLuU8xN5FWYXe2MJEIB58vQYLt4jVfS46xZZR5t5HOolMOpZQfsbQwSJG/4mh 8LHGZeP97f8RRFYDNOxtViZ68mnTq37TA/uj1No1WdrRi2253YQRKHEobfydsWI7nJ/B WgA1ydqY6PZ+uXxEe1dalZOQ2DigYSE5sYBek+hr+DXqxL6+vbwhIrix5gzXo7MVcbr2 4nNA== X-Gm-Message-State: AOAM531A/HOQ0f9LYDCenWxtgxXkuVXjMcr3PBvgzSwWgdN7hibe3a93 5M1ottvzCNMgeG912BfZlkpi90OFrme2OiX+Za8= X-Google-Smtp-Source: ABdhPJxkeX+a0t3UEWcvRnCQEoX2qs85tdDKuKZlwXgE9TpII2Hd+h2Xs6BbQ1qihMSZekjtnFrhn1l9APmiElZ8zt8= X-Received: by 2002:a02:cc54:: with SMTP id i20mr1003818jaq.138.1611868779021; Thu, 28 Jan 2021 13:19:39 -0800 (PST) MIME-Version: 1.0 References: <20210121082451.2240540-1-morbo@google.com> <20210122101156.3257143-1-morbo@google.com> In-Reply-To: Reply-To: sedat.dilek@gmail.com From: Sedat Dilek Date: Thu, 28 Jan 2021 22:19:10 +0100 Message-ID: Subject: Re: [PATCH v7] pgo: add clang's Profile Guided Optimization infrastructure To: Nick Desaulniers Cc: Bill Wendling , Andrew Morton , Jonathan Corbet , Masahiro Yamada , Linux Doc Mailing List , LKML , Linux Kbuild mailing list , clang-built-linux , Nathan Chancellor , Sami Tolvanen Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 28, 2021 at 10:12 PM Nick Desaulniers wrote: > > On Thu, Jan 28, 2021 at 12:46 PM Sedat Dilek wrote: > > > > [ LLVM ] > > > > Today, I switched over to LLVM version 12.0.0-rc1. > > > > > > [ Step #1: 5.11.0-rc5-5-amd64-clang12-pgo ] > > > > My first kernel was built with CONFIG_PGO_CLANG=y and LLVM=1 plus LLVM_IAS=1. > > > > [ start-build_5.11.0-rc5-5-amd64-clang12-pgo.txt ] > > dileks 193090 193065 0 06:54 pts/2 00:00:00 /usr/bin/perf_5.10 > > stat make V=1 -j4 HOSTCC=clang HOSTCXX=clang++ HOSTLD=ld.lld CC=clang > > LD=ld.lld LLVM=1 LLVM_IAS=1 PAHOLE=/opt/pahole/bin/pahole > > LOCALVERSION=-5-amd64-clang12-pgo KBUILD_VERBOSE=1 > > KBUILD_BUILD_HOST=iniza KBUILD_BUILD_USER=sedat.dilek@gmail.com > > KBUILD_BUILD_TIMESTAMP=2021-01-28 bindeb-pkg > > KDEB_PKGVERSION=5.11.0~rc5-5~bullseye+dileks1 > > > > Config: config-5.11.0-rc5-5-amd64-clang12-pgo > > > > > > [ Step #2: x86-64 defconfig & vmlinux.profdata ] > > > > Booted into 5.11.0-rc5-5-amd64-clang12-pgo and built an x86-64 > > defconfig to generate/merge a vmlinux.profdata file. > > > > [ start-build_x86-64-defconfig.txt ] > > dileks 18430 15640 0 11:15 pts/2 00:00:00 make V=1 -j4 > > HOSTCC=clang HOSTCXX=clang++ HOSTLD=ld.lld CC=clang LD=ld.lld LLVM=1 > > LLVM_IAS=1 > > > > Script: profile_clang-pgo.sh > > Config: dot-config.x86-64-defconfig > > > > > > [ Step #3.1: 5.11.0-rc5-6-amd64-clang12-pgo & GNU-AS ] > > > > The first rebuild with CONFIG_PGO_CLANG=n and "LLVM=1 > > KCFLAGS=-fprofile-use=vmlinux.profdata". > > I was able to boot into this one. > > Used assembler: GNU-AS 2.35.1 > > > > [ start-build_5.11.0-rc5-6-amd64-clang12-pgo.txt ] > > dileks 65734 65709 0 11:54 pts/2 00:00:00 /usr/bin/perf_5.10 > > stat make V=1 -j4 HOSTCC=clang HOSTCXX=clang++ HOSTLD=ld.lld CC=clang > > LD=ld.lld PAHOLE=/opt/pahole/bin/pahole > > LOCALVERSION=-6-amd64-clang12-pgo KBUILD_VERBOSE=1 > > KBUILD_BUILD_HOST=iniza KBUILD_BUILD_USER=sedat.dilek@gmail.com > > KBUILD_BUILD_TIMESTAMP=2021-01-28 bindeb-pkg > > KDEB_PKGVERSION=5.11.0~rc5-6~bullseye+dileks1 LLVM=1 > > KCFLAGS=-fprofile-use=vmlinux.profdata > > > > Config: config-5.11.0-rc5-6-amd64-clang12-pgo > > > > > > [ Step #3.2: 5.11.0-rc5-7-amd64-clang12-pgo & Clang-IAS ] > > > > The second rebuild with CONFIG_PGO_CLANG=n and "LLVM=1 > > KCFLAGS=-fprofile-use=vmlinux.profdata" plus LLVM_IAS=1. > > Compilable but NOT bootable in QEMU and on bare metal. > > Used assembler: Clang-IAS v12.0.0-rc1 > > > > [ start-build_5.11.0-rc5-7-amd64-clang12-pgo.txt ] > > dileks 6545 6520 0 16:31 pts/2 00:00:00 /usr/bin/perf_5.10 > > stat make V=1 -j4 HOSTCC=clang HOSTCXX=clang++ HOSTLD=ld.lld CC=clang > > LD=ld.lld PAHOLE=/opt/pahole/bin/pahole > > LOCALVERSION=-7-amd64-clang12-pgo KBUILD_VERBOSE=1 > > KBUILD_BUILD_HOST=iniza KBUILD_BUILD_USER=sedat.dilek@gmail.com > > KBUILD_BUILD_TIMESTAMP=2021-01-28 bindeb-pkg > > KDEB_PKGVERSION=5.11.0~rc5-7~bullseye+dileks1 LLVM=1 > > KCFLAGS=-fprofile-use=vmlinux.profdata LLVM_IAS=1 > > > > Config: config-5.11.0-rc5-7-amd64-clang12-pgo > > > > > > [ Conclusion ] > > > > The only statement I can tell you is a "PGO optimized" rebuild with > > LLVM_IAS=1 is compilable but NOT bootable. > > Thanks for the extensive testing and report. Can you compress, upload, > and post a link to your kernel image? I would like to take it for a > spin in QEMU and see if I can find what it's doing, then work > backwards from there. > Which files do you need? For QEMU: bzImage and initrd.img enough? - Sedat -