From owner-freebsd-hackers@FreeBSD.ORG  Sun Jun  2 18:07:55 2013
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115])
 by hub.freebsd.org (Postfix) with ESMTP id 79594117
 for <freebsd-hackers@freebsd.org>; Sun,  2 Jun 2013 18:07:55 +0000 (UTC)
 (envelope-from adrian.chadd@gmail.com)
Received: from mail-qc0-x22d.google.com (mail-qc0-x22d.google.com
 [IPv6:2607:f8b0:400d:c01::22d])
 by mx1.freebsd.org (Postfix) with ESMTP id 4239F11E9
 for <freebsd-hackers@freebsd.org>; Sun,  2 Jun 2013 18:07:55 +0000 (UTC)
Received: by mail-qc0-f173.google.com with SMTP id c11so1746427qcv.32
 for <freebsd-hackers@freebsd.org>; Sun, 02 Jun 2013 11:07:54 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113;
 h=mime-version:sender:in-reply-to:references:date
 :x-google-sender-auth:message-id:subject:from:to:cc:content-type;
 bh=SQfM4LrcJZHBlLwW/Jix4tqbnXngFij41WfLGLwjYw4=;
 b=Y6bEpCmQeXRiuOLAWuY1QRT5S4vlKieoCpW1UmXTj+n5XBgznTrn2UqbJfjOezY+7g
 EPv1SexK1tnnXZLDTOGlraAyvHlTGGSr6W7bRPIgDhSZPkYB/IQxmOBt1o/d7mXWdD5s
 OQwgjjoq66uaVcXHzwpKvW5ur8vTUuqTwO4ngGG7ulPPlJj5NreJhlQTQ8zaj3Wxn74S
 9dyS7K6vGqXcpjbi/zY+aZJXFPCGBTfhb2RnXiRmP1SxtXf3KgxZYo+61DHp8XBQQsel
 pMcXlql49GTdgvB7wElcKNgyGgBRVRq7NLelu9oxu2pjhKYalnJsx0L2jr2eiXPHywVK
 +izA==
MIME-Version: 1.0
X-Received: by 10.224.172.1 with SMTP id j1mr16070706qaz.15.1370196474818;
 Sun, 02 Jun 2013 11:07:54 -0700 (PDT)
Sender: adrian.chadd@gmail.com
Received: by 10.224.71.12 with HTTP; Sun, 2 Jun 2013 11:07:54 -0700 (PDT)
In-Reply-To: <CADLo838JALaTwdSjy+V0JMHkbz1mD+ezOq7a=dRzeNaSeUrDEg@mail.gmail.com>
References: <CADLo838JALaTwdSjy+V0JMHkbz1mD+ezOq7a=dRzeNaSeUrDEg@mail.gmail.com>
Date: Sun, 2 Jun 2013 11:07:54 -0700
X-Google-Sender-Auth: 1lrmBOjnTEgCzUvXd79Rpu1LnK4
Message-ID: <CAJ-Vmo=xkeJ3T28W6b++mXCiNmOngxxsQyRD3Gx1Tx1Nr3ncPg@mail.gmail.com>
Subject: Re: sed query
From: Adrian Chadd <adrian@freebsd.org>
To: Chris Rees <utisoft@gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Cc: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.14
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
 <freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-hackers>, 
 <mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
 <mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 02 Jun 2013 18:07:55 -0000

... so run it inside hwpmc and see what the resulting CPU users are?



adrian

On 31 May 2013 07:01, Chris Rees <utisoft@gmail.com> wrote:
> Hi all,
>
> I think I've discovered a strange behaviour of sed perhaps triggered
> by the length of a regex passed to it.  I noticed that a certain
> expression I passed took a very long time, and suspected the usual
> backtracking loop, so I started trimming it... and discovered this:
>
> [crees@pegasus]~% time sed -ne "s,^BitchX-[0-9][^|]*[\|]/usr/por,,"
> /var/db/pkg/INDEX-9
> 4.699u 0.007s 0:04.70 99.7% 40+2733k 0+0io 0pf+0w
> [crees@pegasus]~% time sed -ne "s,^BitchX-[0-9][^|]*[\|]/usr/po,,"
> /var/db/pkg/INDEX-9
> 0.042u 0.000s 0:00.04 100.0% 48+3216k 0+0io 0pf+0w
>
> I've looked at the code, and can't from a brief glance figure out why
> a slightly longer regex makes such a difference-- does it start to
> split it?
>
> Chris
> _______________________________________________
> freebsd-hackers@freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
> To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org"