From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 18908 invoked by alias); 21 Jan 2009 15:29:50 -0000 Received: (qmail 18900 invoked by uid 22791); 21 Jan 2009 15:29:49 -0000 X-SWARE-Spam-Status: No, hits=-1.6 required=5.0 tests=AWL,BAYES_00,KAM_MX,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (66.187.233.31) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 21 Jan 2009 15:29:41 +0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id n0LFTdQb023768 for ; Wed, 21 Jan 2009 10:29:39 -0500 Received: from ns3.rdu.redhat.com (ns3.rdu.redhat.com [10.11.255.199]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n0LFTeVw014777 for ; Wed, 21 Jan 2009 10:29:40 -0500 Received: from redhat.com (dhcp-100-19-102.bos.redhat.com [10.16.19.102]) by ns3.rdu.redhat.com (8.13.8/8.13.8) with ESMTP id n0LFTde2024907; Wed, 21 Jan 2009 10:29:39 -0500 Date: Wed, 21 Jan 2009 16:42:00 -0000 From: Jason Baron To: linux-kernel@vger.kernel.org Cc: Linux NFS ML , Linux NFSv4 ML , SystemTAP ML , gnb@sgi.com Subject: Re: [patch 0/5] activate & deactivate dprintks individually and severally Message-ID: <20090121152858.GA23953@redhat.com> References: <20090120012930.020621000@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090120012930.020621000@sgi.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2009-q1/txt/msg00202.txt.bz2 On Tue, Jan 20, 2009 at 12:29:30PM +1100, Greg Banks wrote: > > As mentioned in the recent discussion on NFS trace points on the NFS & > SystemTap mailing lists. This patch allows field support staff and > kernel developers debug kernel problems, by enabling them to treat > dprintks as precise trace points rather than syslog spamming tools. > > This is a forward ported (from 2.6.16), updated, and split version > of a patch that has been used in SGI's internal development tree for > the last few months. The very first version of this was used about > eighteen months ago when debugging NFS/RDMA, which has an enormous > number of dprintks and no other way to debug it. > > Jason Baron suggested I post it here for review and contrast with > his dynamic dprintk feature. > yes, these two patch sets are very similar in the problem that they are addressing. For me, one of the core differences, is that 'dprintk' has per-debug statement control, while my solution, 'dynamic debug' has a more per-module focused control. 'dprintk' thus checks a different variable per-debug line to see if its enabled. On the other hand 'dynamic debug' can check 1 global variable (in the most common cases), to see if its enabled or not. I think we can layer per-line check on top of the 1 global variable check and have a more efficient solution that still allows for fine-grained debugging. 'dprintk' also has a richer user interface, which allows for file, line, module, and statement control. Thus, I think Greg and I can work together and combine the best features of both patches. We will re-post a combined solution. thanks, -Jason