From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 104607 invoked by alias); 18 Jun 2017 16:50:47 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 104594 invoked by uid 89); 18 Jun 2017 16:50:46 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-6.9 required=5.0 tests=BAYES_00,GIT_PATCH_1,SPF_HELO_PASS,T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 spammy=invests X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Sun, 18 Jun 2017 16:50:45 +0000 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9E62890907; Sun, 18 Jun 2017 16:50:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 9E62890907 Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=jan.kratochvil@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 9E62890907 Received: from host1.jankratochvil.net (ovpn-116-67.ams2.redhat.com [10.36.116.67]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B06F218220; Sun, 18 Jun 2017 16:50:47 +0000 (UTC) Date: Sun, 18 Jun 2017 16:50:00 -0000 From: Jan Kratochvil To: Pedro Alves Cc: gdb-patches@sourceware.org, Victor Leschuk Subject: Re: [pushed] Re: [PATCH 1/6] Code cleanup: C++ify .gdb_index producer. Message-ID: <20170618165045.GA6469@host1.jankratochvil.net> References: <149582312757.15869.18345460438195439402.stgit@host1.jankratochvil.net> <149582313928.15869.12647134810146005233.stgit@host1.jankratochvil.net> <8efc0742-1014-4fe0-6948-f40a9c5c4975@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8efc0742-1014-4fe0-6948-f40a9c5c4975@redhat.com> User-Agent: Mutt/1.8.0 (2017-02-23) X-SW-Source: 2017-06/txt/msg00479.txt.bz2 On Mon, 12 Jun 2017 18:08:07 +0200, Pedro Alves wrote: > Note that this patch as is actually causes a ~10% performance > drop in .gdb_index generation that can be significant when > running gdb index on big binaries or in a a batch of binaries. gdb-add-index is being used in Koji builds where it takes minutes to build even a trivial package. Otherwise I do not see why anyone would use it for C++ programs edit-compile-debug cycles where the speed matters: 0m 5.389s -fuse-ld=gold -Wl,--gdb-index,--build-id 0m 3.564s -fuse-ld=gold -Wl,--build-id 1.825s = --gdb-index part of gold 0m19.401s (GNU ld) -Wl,--build-id 0m 4.364s gdb-add-index 23.765s = GNU ld + gdb-add-index 23.765 / 5.389 = 4.4099090740397102 GNU ld is too slow and then gold can already produce .gdb_index along its linking in just negligible time. Just gold is not a default linker as discussed in: [PATCH] [BZ #14995] glibc fails to build if gold is the default linker, even if ld.bfd is available https://sourceware.org/ml/libc-alpha/2015-03/msg00410.html and in my mail internally in Red Hat: Subject: [debug-list] DWARF5 .debug_names vs. .gdb_index vs. two lds Message-ID: <20161027162728.GA6631@host1.jankratochvil.net> Although nobody invests time to fix gold to finally switch to it. But then the currently missing support for DWO in .debug_names seems to be pointless to implement into GDB as DWO is used only for better edit-compile-debug cycle speed but then one cannot use GNU ld and so DWO .debug_names support should be implemented rather into gold. Jan