From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752469AbeDLNFT (ORCPT ); Thu, 12 Apr 2018 09:05:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:45418 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751448AbeDLNFR (ORCPT ); Thu, 12 Apr 2018 09:05:17 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1B77521745 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=acme@kernel.org Date: Thu, 12 Apr 2018 10:05:13 -0300 From: Arnaldo Carvalho de Melo To: Thomas Richter Cc: linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, brueckner@linux.vnet.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com Subject: Re: [PATCH] perf record: Remove unnecessary warning for missing sysfs entry Message-ID: <20180412130513.GB9818@kernel.org> References: <20180412114723.48550-1-tmricht@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180412114723.48550-1-tmricht@linux.ibm.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Thu, Apr 12, 2018 at 01:47:23PM +0200, Thomas Richter escreveu: > Using perf on 4.16.0 kernel on s390 shows warning > failed: can't open node sysfs data > each time I run command perf record ... for example: > > [root@s35lp76 perf]# ./perf record -e rB0000 -- sleep 1 > [ perf record: Woken up 1 times to write data ] > failed: can't open node sysfs data > [ perf record: Captured and wrote 0.001 MB perf.data (4 samples) ] > [root@s35lp76 perf]# > > BTW: I find this error message not very informative. What an understatement :-) > It turns out commit e2091cedd51bf ("perf tools: Add MEM_TOPOLOGY > feature to perf data file") tries to open directory named > /sys/devices/system/node/ which does not exist on s390. > > This is the call stack: > __cmd_record > +---> perf_session__write_header > +---> perf_header__adds_write > +---> do_write_feat > +---> write_mem_topology > +---> build_mem_topology > prints warning > The issue starts in do_write_feat() which unconditionally > loops over all features and now includes HEADER_MEM_TOPOLOGY and calls > write_mem_topology(). > Function record__init_features() at the beginning of __cmd_record() > sets all features and then turns off some. > > Fix this by removed the warning, if the directory is not present > memory node information is not available and won't be displayed. Can't we instead improve the error message and turn this into a pr_debug2? Isn't it a reasonable scenario that the user expects this topology information to be present and then ends up without it? Perhaps something like: pr_debug2("%s: could't read %s, does this arch have topology information?\n", __func__, path); - Arnaldo > Signed-off-by: Thomas Richter > --- > tools/perf/util/header.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c > index 121df1683c36..4a3bfc900a68 100644 > --- a/tools/perf/util/header.c > +++ b/tools/perf/util/header.c > @@ -1320,7 +1320,6 @@ static int build_mem_topology(struct memory_node *nodes, u64 size, u64 *cntp) > > dir = opendir(path); > if (!dir) { > - pr_warning("failed: can't open node sysfs data\n"); > return -1; > } > > -- > 2.14.3