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=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 83A3FC43613 for ; Thu, 20 Jun 2019 20:38:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5400E2082C for ; Thu, 20 Jun 2019 20:38:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="drTB1igf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726129AbfFTUiu (ORCPT ); Thu, 20 Jun 2019 16:38:50 -0400 Received: from mail-ed1-f66.google.com ([209.85.208.66]:45363 "EHLO mail-ed1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725815AbfFTUiu (ORCPT ); Thu, 20 Jun 2019 16:38:50 -0400 Received: by mail-ed1-f66.google.com with SMTP id a14so6495523edv.12 for ; Thu, 20 Jun 2019 13:38:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=3NNpxQC9inEMdQiCtKdevzqLpK6p/o11oFFffa2tXtA=; b=drTB1igfYgyVGqDFahZ5NCLWxeC+zgZym5tNhHU9P8EVSYWsif8ATO7pGEP+d9b4jh JAOnze86pJuhlaTw0qlD/nW6rmrmbt2IBo7iigDcsRG6wUQWA25EcHINzbbeiMWc6kbv TIuJ7KJQbLsp195+3AwE47Er77voagXXJT1rsAjFejlw31omdfGinBG6DPOUaGItFu+D ys8HdSTj7s+FDlec/VPr03RWlEH28OKXZuN5/b58TkSNoU+KY/KedGOeatIk/zPPPXh0 /tB97o72J1eTHRzAcS1bmSx1VBukLqxVclGb2OyRv47B3yeHVfSUQUjUoYCoslao1nwy iMOw== 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:user-agent; bh=3NNpxQC9inEMdQiCtKdevzqLpK6p/o11oFFffa2tXtA=; b=Xv+x6F6WxapgwKqTgv1wIW7DFHARCHFFpIvvaVqA2BVdK+sTFKN8gD5UlFRlIV+FW3 EfQaulFSHDCzha7UQPRLuEGVYaGFbPwvI6PwMyKF3F1Vs3MU0VHpKMUzAqaNNddBGzEc +v7qkmSaIMeSjwUzfEiF0uBAm768g9TIcA+5u4gusN9vGL0NZSL/1Pei1uy9BiFpJkeW 2mWPgOICH68O5hZlng9BdQscc0eWx3FyhcZ+KfG3XeXPWYnVtCd8xwjlrtbQf+y9TCNC 8yufn50sRgwf8REAvt7Dj3wc73L2bYtvzfTX33vazkv985ziuk9Xnny96DW+gfkM+ZRN 5qyA== X-Gm-Message-State: APjAAAUud7mQsjIOfKgXv2/RFTxtg3UV+5Nc6NCU6JVW9ABPhOj5tfCB +ZyW2yJcbewCvn7IERSRZr9PmleRPeMOdQ== X-Google-Smtp-Source: APXvYqyFv7TcKmDYh6aGGxLZIuOvRIKKOd88Mr+MJzIGjGqg4v29rEZylk+bGGm4BsLzINtBP1v0qQ== X-Received: by 2002:a17:906:3385:: with SMTP id v5mr112020844eja.301.1561063128315; Thu, 20 Jun 2019 13:38:48 -0700 (PDT) Received: from archlinux-epyc ([2a01:4f9:2b:2b15::2]) by smtp.gmail.com with ESMTPSA id g6sm69844ejb.18.2019.06.20.13.38.47 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Thu, 20 Jun 2019 13:38:47 -0700 (PDT) Date: Thu, 20 Jun 2019 13:38:45 -0700 From: Nathan Chancellor To: Nick Desaulniers Cc: Doug Anderson , Matthias Kaehlcke , Tom Roeder , Masahiro Yamada , LKML , Raul E Rangel , Tom Hughes , Ryan Case , Yu Liu Subject: Re: [PATCH] gen_compile_command: Add support for separate KBUILD_OUTPUT directory Message-ID: <20190620203845.GA102280@archlinux-epyc> References: <20190620184523.155756-1-mka@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 20, 2019 at 01:25:36PM -0700, Nick Desaulniers wrote: > On Thu, Jun 20, 2019 at 1:13 PM Doug Anderson wrote: > > On Thu, Jun 20, 2019 at 12:53 PM Nick Desaulniers > > wrote: > > > > > > I do miss Doug's Kbuild caching patches' speedup. > > > > You actually get quite a bit of this by grabbing a new version of > > ccache (assuming you use ccache). :-P You still have to pay the > > penalty (twice) for all the options that are tested that the compiler > > _doesn't_ support, but at least you get the cache for the commands > > that the compiler does support. > > Hello darkness my old friend: > https://nickdesaulniers.github.io/blog/2018/06/02/speeding-up-linux-kernel-builds-with-ccache/ > Man, that post has not aged well. Here's what we do now: > https://github.com/ClangBuiltLinux/continuous-integration/blob/45ab5842a69cb0c72d27d34e73b0599ec2a0e2ed/driver.sh#L227-L245 > > > Specifically, make sure you have a ccache with: > > > > * https://github.com/ccache/ccache/pull/365 > > * https://github.com/ccache/ccache/pull/370 > > Oh! Interesting finds and thanks for the pointers. Did these make it > into a release version of ccache, yet? If so, do you know which > version? > It should be available in 3.7 if I am reading git history right. Cheers, Nathan > > I still have it in my thoughts to avoid the penalty for options that > > the compiler doesn't support but haven't had time to work on it > > recently. > > It had better not be autoconf! (Hopefully yet-to-be-written GNU C > extensions can support feature detection via C preprocessor) > -- > Thanks, > ~Nick Desaulniers