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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9F901C79FB7 for ; Wed, 9 Sep 2026 16:30:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=PLsESkA+Fqpa5SFN+E4JUVghuzcLb17M41Y7o0f/c4w=; b=mYGahOBuYfjFsi WHRl2YAYWwRhmEVQa1/vXF0Ml9hw2GlXJgEcdIoOczdd0g5WlWhfYm61FuvhvSe8Qb1EABJ2UKa8E rGqXCoszqo5ZCGFaSFLJerzJbcTSwdPvgAAdHaLZhKelij4nXKHNF2R74Po4iqa7Ti1Z/ggydB4mL R2AY0mWMCiJgRbLZyamXG6oT+UFRTX5xOgu1nobl472hUaB7LzFczC9zam/uFJBHaiSDUE4S3jrCb etrQeoRDMXCRhHvlBbM766TuRCbY/SZnB1sqUAe7vrPupI/CfBWvXfMGAYiKET1XdeMSM35+OPdao RQKSWykcIQuXlP5MgefA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x4LC1-0000000CJQT-1qXx; Wed, 09 Sep 2026 16:30:37 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x4LBz-0000000CJPv-3Zq9; Wed, 09 Sep 2026 16:30:35 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 89CD160204; Wed, 9 Sep 2026 16:30:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0AFE61F000FF; Wed, 9 Sep 2026 16:30:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788971434; bh=Kz7rWeqwh7ufJDv87BxiJfD/gwwv4aMAp/7XS3gBPEo=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=dcYf5Ku63ij8aECQoJafs4Ipg1pK9oXj9HMZSoM3ml9RYUs9bgWbI892r15HKD+aq TO6FjMT8mTQhfp+iMomWORtQlAM3jIsyaPwYZSaHoJn7R/JGCghwy4f2f0niwav6ni eBJdRLPFcGRmhIBelQgMN8TiQon3ZGk+0ZjUxsPj6ZoUq1f644nJlygEq9jKwgJozp ivMzm6l0Cf1qm0bdrELXOXxe7OHf/vwZsgJpnbZUDSpqIhRXP81TW35ZC+juNo5mm5 w8CyZDKbmN2fe9Tm4ZiwdQMSYdgzFqNx03fbVBS+oujn39g8U1gp6xIrrIUpTbPfjZ fo6l8mjP/fXXQ== Date: Wed, 9 Sep 2026 17:30:19 +0100 From: "Lorenzo Stoakes (ARM)" To: Linus Torvalds Cc: Nathan Chancellor , Nicolas Schier , Nick Desaulniers , Bill Wendling , Justin Stitt , Masahiro Yamada , Alexey Gladkov , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Arnd Bergmann , Catalin Marinas , Will Deacon , Mark Rutland , Ard Biesheuvel , Ilias Apalodimas , Josh Poimboeuf , Peter Zijlstra , Miguel Ojeda , Boqun Feng , Gary Guo , =?utf-8?B?QmrDtnJu?= Roy Baron , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , Onur =?utf-8?B?w5Z6a2Fu?= , Jonathan Corbet , Randy Dunlap , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, linux-riscv@lists.infradead.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-efi@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-doc@vger.kernel.org, Jens Axboe Subject: Re: [PATCH 00/23] kbuild: significantly speed up kernel builds Message-ID: References: <20260908-build-speedup-v1-0-5dc1ac01672d@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Wed, Sep 09, 2026 at 08:37:10AM -0700, Linus Torvalds wrote: > On Tue, 8 Sept 2026 at 13:55, Lorenzo Stoakes (ARM) wrote: > > > > A typical kernel build consists of a frustratingly large amount of time > > .. you're preaching to the choir. :) Yeah, it's something that's annoyed me for a long time too. > > > == allmodconfig FULL build == > > > > before after delta > > ---------------------------------- > > Threadripper, gcc 345.3s 275.2s -70.1s (-20%) > > Well, that's certainly very encouraging. We should do this. I sent out > some emails as just reactions to individual patches, but I have no > numbers to back any of those emails up, and I never actually applied > this series to my tree - they were all based on reading the patches > themselves. Thanks, will have a read through those! I do recommend trying them locally ;) It makes a surprising difference to defconfig even. (Though you need pigz installed for the full effect) > > That said: > > > An LLM was used to first determine where the bottlenecks were then to > > figure out how to improve them. > > > > It generated a lot of code, much of it hideous. > > This made me scared to look at the patches originally, and I held off > in fear that the patches would be horrible and this build time > improvement would be hugely controversial garbage code. > > But: > > > I extensively audited and rewrote a lot of it, and heavily edited commit > > messages, the cover letter and comments. > > None of the patches look at all horrible to me. You clearly excised > the hideous parts. All of my reactions were of the type "this could > probably be taken _further_" rather than me throwing my hands up in > disgust. Thanks! :) I made sure to audit everything it came up with patch-by-patch, got it to rework the horrors then rewrote large chunks of what it came up with. > > So the Rust parallelism thing clearly isn't ready based on feedback > from that quarter, but the rest looked safe and innocuous. I'm all for Sure, happy to drop anything like that. Though based on what Miguel said it _might_ be ok perhaps with a nightly gate on it? Will see what he/Bjorn say. > merging this, although it should obviously go in through the right > channels. Mostly the kbuild tree, although some of it clearly would be > other cases - the objtool change in particular is fairly substantial > and needsobjtool people to approve. It didn't look all that > contentious, but still.. Agreed, it definitely needs some eyes on it, especially the trickier bits. > > Anyway, I'd love for this all to go in. Build times are a pet peeve of mine. Yeah, it'd be nice to see this benefit everyone! Am happy to iterate on it as needed to get it upstream. > > Linus -- Cheers, Lorenzo _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv