Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753196Ab3JBGFW (ORCPT ); Wed, 2 Oct 2013 02:05:22 -0400 Received: from lgeamrelo02.lge.com ([156.147.1.126]:61870 "EHLO LGEAMRELO02.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752718Ab3JBGFT (ORCPT ); Wed, 2 Oct 2013 02:05:19 -0400 X-AuditID: 9c93017e-b7ca5ae0000013bb-20-524bb79d1561 From: Namhyung Kim To: Ingo Molnar Cc: Arnaldo Carvalho de Melo , David Ahern , Linus Torvalds , Linux Kernel Mailing List , Peter Zijlstra , Thomas Gleixner , Andrew Morton , Jiri Olsa Subject: Re: [PATCH] perf auto-dep: Speed up feature tests by building them in parallel References: <20130912133855.GA23780@gmail.com> <20130912184341.GA11400@ghostprotocols.net> <52321CE4.1080804@gmail.com> <20130912200236.GC11400@ghostprotocols.net> <20130912203116.GD32644@gmail.com> <20130912204313.GA3259@gmail.com> <20130915091029.GA21465@gmail.com> <20130930164210.GA22342@gmail.com> Date: Wed, 02 Oct 2013 15:05:17 +0900 In-Reply-To: <20130930164210.GA22342@gmail.com> (Ingo Molnar's message of "Mon, 30 Sep 2013 18:42:10 +0200") Message-ID: <87zjqsmcma.fsf@sejong.aot.lge.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2202 Lines: 53 Hi Ingo, On Mon, 30 Sep 2013 18:42:10 +0200, Ingo Molnar wrote: > This series (with combo patch attached) implements (much) faster > perf-tools feature-auto-detection. > > I used 3 tricks to implement feature auto-dependencies and to speed up > feature detection: > > - standalone Makefile in config/feature-checks/ built in parallel > > - split-out standalone .c files in config/feature-checks/*.c > > - used GCC's auto-dependency generation feature (-MD) to track the > effects of system library addition/removal. I have a memory that this could lead to a nasty build failure. Please see the commit b6f4f804108b ("tools lib traceevent: Do not generate dependency for system header files"). The problem is that it turned out to depend on some compiler headers which are located under some directory with a version number. If so, when compiler upgraded to a new version, it cannot find the original dependencies so fail to build. $ cat config/feature-checks/test-libelf.d test-libelf: test-libelf.c /usr/include/libelf.h /usr/include/sys/types.h \ /usr/include/features.h /usr/include/stdc-predef.h \ /usr/include/sys/cdefs.h /usr/include/bits/wordsize.h \ /usr/include/gnu/stubs.h /usr/include/gnu/stubs-64.h \ /usr/include/bits/types.h /usr/include/bits/typesizes.h \ /usr/include/time.h \ /usr/lib/gcc/x86_64-redhat-linux/4.7.2/include/stddef.h \ /usr/include/endian.h /usr/include/bits/endian.h \ /usr/include/bits/byteswap.h /usr/include/bits/byteswap-16.h \ /usr/include/sys/select.h /usr/include/bits/select.h \ /usr/include/bits/sigset.h /usr/include/bits/time.h \ /usr/include/sys/sysmacros.h /usr/include/bits/pthreadtypes.h \ /usr/include/elf.h \ /usr/lib/gcc/x86_64-redhat-linux/4.7.2/include/stdint.h \ /usr/include/stdint.h /usr/include/bits/wchar.h In this case we are using this for feature-checking, so I guess it'd fail to check the feature after upgrade. Thanks, Namhyung -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/