From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932361Ab2IQQCS (ORCPT ); Mon, 17 Sep 2012 12:02:18 -0400 Received: from mail-yw0-f46.google.com ([209.85.213.46]:36951 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932236Ab2IQQCR (ORCPT ); Mon, 17 Sep 2012 12:02:17 -0400 Date: Mon, 17 Sep 2012 09:02:11 -0700 From: Arnaldo Carvalho de Melo To: David Ahern Cc: Andrew Jones , linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, paulus@samba.org, mingo@redhat.com, tzanussi@gmail.com Subject: Re: perf script: rwtop: SIGALRM and pipe read race Message-ID: <20120917160211.GC31375@ghostprotocols.net> References: <20120914153952.GA8834@turtle.usersys.redhat.com> <505355AF.7000006@gmail.com> <20120914181049.GA16618@turtle.usersys.redhat.com> <505739EF.5010000@gmail.com> <50573EC3.6020209@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <50573EC3.6020209@gmail.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Mon, Sep 17, 2012 at 09:16:19AM -0600, David Ahern escreveu: > On 9/17/12 8:55 AM, David Ahern wrote: > >2. the rwtop.pl script is not handling negative return values ($ret < 0) > >properly -- the '$ret > 0' check is succeeding even though $ret is > >negative (e.g., -EAGAIN) leading to astronomical read values > > I think perl is treating $ret as an unsigned integer. > > Again, I know little about perl, but this change to > ./scripts/perl/rwtop.pl makes it behave properly: > > my $n = sprintf("%d", $ret); > > if ($n > 0) { > ... I think what you figured out makes sense, its the best we have and you found it to get it back working, could you please send the two patches properly signed-off, etc? If Andrew could please test the patchset so that I could add his Tested-by, that would be great, Thanks, - Arnaldo