From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 68CBE2110B; Mon, 22 Jan 2024 08:32:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.132 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705912354; cv=none; b=ksdP0qfb+rrtrEIAq5RHccOfk68Rj2lr9YS8bJ1pH78ndN3j+SCQmKvYbxFT62CLcpEEo9msf+0bDonc6ZQKsaeMLId5kOekx4ecdpgdf1bbxw3LAZ3O2+gn/QalSzRq8J8y8omDC88Qxsv8LFAWKzIrbtXa94zzCjkQtqxhQXE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705912354; c=relaxed/simple; bh=hI3RltjIMGXevPYm0LRBHuDZvSVHVegDJEQwPNgLkhk=; h=Message-ID:Date:MIME-Version:From:Subject:To:Cc:Content-Type; b=TfekZDLkKEXKuWyXMoK/GOg97uPWKvPLddywvUppNCRf9RH/LAp77rOledWPERahFnyBOMEtEYErKszsFCzOPFaR7FpQipqY5knMlqd4ahy1noOsVf24gaq97u9y3yocxarM5lk5qnbeeyx7roJpaRCXlaysywwl6TanI3L537U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; arc=none smtp.client-ip=115.124.30.132 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R161e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046056;MF=jefflexu@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0W.5I.B1_1705912333; Received: from 30.221.145.129(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0W.5I.B1_1705912333) by smtp.aliyun-inc.com; Mon, 22 Jan 2024 16:32:26 +0800 Message-ID: Date: Mon, 22 Jan 2024 16:32:26 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Content-Language: en-US From: Jingbo Xu Subject: [MAYBE REGRESSION] kbuild time of kernel compiling To: linux-kbuild@vger.kernel.org, masahiroy@kernel.org, nathan@kernel.org, ndesaulniers@google.com, nicolas@fjasle.eu Cc: "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, I noticed a regression of kbuild time in v6.7, especially when running `make` command when all images have already been compiled. In v6.6 it takes ~3s, while in v6.7 it takes ~18s. I'm not sure if it's a known issue, or an extra action configurable with a "CONFIG_XX" option. Following is the kbuild time in v6.6 versus v7.7, with arch/x86/configs/x86_64_defconfig used here: v6.6 ``` make clean make olddefconfig # first full compiling $time make bzImage -j128 -s real 1m9.896s user 36m56.153s sys 4m21.748s # second time with image already compiled $time make bzImage -j128 -s real 0m2.776s user 0m13.823s sys 0m3.936s ``` v6.7 ``` make clean make olddefconfig # first full compiling $time make bzImage -j128 -s real 1m22.865s user 37m25.977s sys 4m22.094s # second time with image already compiled $time make bzImage -j128 -s real 0m18.209s user 0m29.243s sys 0m4.330s ``` I tried to bisect, while commit d4e175f2c460 ("Merge tag 'vfs-6.7.super' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs") is identified as the first bad commit, which is obviously wrong. As I'm not familiar with the structure of the merge commit, the further investigation has not been made yet. Besides, it seems that it will take most of the time before "CALL scripts/checksyscalls.sh" is printed (with "INSTALL libsubcmd_headers" has already printed). $time make bzImage -j128 DESCEND objtool INSTALL libsubcmd_headers CALL scripts/checksyscalls.sh BUILD arch/x86/boot/bzImage Kernel: arch/x86/boot/bzImage is ready (#437) -- Thanks, Jingbo