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=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no 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 8143BC282DD for ; Wed, 8 Jan 2020 14:35:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 56FCE206F0 for ; Wed, 8 Jan 2020 14:35:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="iXYX0Y2s" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728135AbgAHOfe (ORCPT ); Wed, 8 Jan 2020 09:35:34 -0500 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:54339 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726411AbgAHOfe (ORCPT ); Wed, 8 Jan 2020 09:35:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578494132; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=fP+WPZXzfTrcd6wkGC25b1jea+qaX/5G0Sorwuc2/9o=; b=iXYX0Y2slOdtiqHLYimPUSe6gCR0YYAt92PSQN3edcZxMnIDYkroqUHPzS3KYMfnRTwHJ5 eHw2TSlUlVABeVDSzqYRY26fktqDavvPqIHLNQLGumomFsBmY4TiH2un/KGUtsa9CN/TEP s2btbIstJQtNWbqNJYGMTp3K5LpIaSM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-336-4AOAtzb6MzC3zwH2BoJp3g-1; Wed, 08 Jan 2020 09:35:30 -0500 X-MC-Unique: 4AOAtzb6MzC3zwH2BoJp3g-1 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id 55C971005502; Wed, 8 Jan 2020 14:35:28 +0000 (UTC) Received: from krava (ovpn-204-186.brq.redhat.com [10.40.204.186]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7B07886C5E; Wed, 8 Jan 2020 14:35:25 +0000 (UTC) Date: Wed, 8 Jan 2020 15:35:22 +0100 From: Jiri Olsa To: "Jin, Yao" Cc: acme@kernel.org, jolsa@kernel.org, peterz@infradead.org, mingo@redhat.com, alexander.shishkin@linux.intel.com, Linux-kernel@vger.kernel.org, ak@linux.intel.com, kan.liang@intel.com, yao.jin@intel.com, tmricht@linux.ibm.com Subject: Re: [PATCH] perf report: Fix no libunwind compiled warning break s390 issue Message-ID: <20200108143522.GE387467@krava> References: <20200107191745.18415-1-yao.jin@linux.intel.com> <20200108102708.GC360164@krava> <7b88fdcc-9603-d3e1-d43b-b8fb8b394f70@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7b88fdcc-9603-d3e1-d43b-b8fb8b394f70@linux.intel.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 08, 2020 at 09:02:02PM +0800, Jin, Yao wrote: > > > On 1/8/2020 6:27 PM, Jiri Olsa wrote: > > On Wed, Jan 08, 2020 at 03:17:45AM +0800, Jin Yao wrote: > > > Commit 800d3f561659 ("perf report: Add warning when libunwind not compiled in") > > > breaks the s390 platform. S390 uses libdw-dwarf-unwind for call chain > > > unwinding and had no support for libunwind. > > > > > > So the warning "Please install libunwind development packages during the perf build." > > > caused the confusion even if the call-graph is displayed correctly. > > > > > > This patch adds checking for HAVE_DWARF_SUPPORT, which is set when > > > libdw-dwarf-unwind is compiled in. > > > > > > Fixes: 800d3f561659 ("perf report: Add warning when libunwind not compiled in") > > > > > > Reviewed-by: Thomas Richter > > > Tested-by: Thomas Richter > > > Signed-off-by: Jin Yao > > > > perfect, I have the same change prepared for sending, but it's > > together with making libdw default dwarf unwinder, which I'm still > > not sure we want to do, so it all got posponed ;-) > > > would you guys be ok with that? with having libdw picked up as > default dwarf unwinder.. > > > > I've roughly compared the performance between libunwind-dev and libdw-dev. > While in my test (on KBL desktop), for the same perf report command-line, it > looks the perf built with libunwind-dev is much faster than the perf built > with libdw-dev. ok, that's valid point.. the reason we start discussing it, was that libunwind does not seem to support compressed ELF debug sections, which works via libdw unwind > > The command line is as following: > > perf record --call-graph dwarf ./div > perf report -g graph --stdio I'll try to do some profiling and check with outr contact in libdw to comment/check on that thanks, jirka