From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20901 invoked by alias); 6 Jul 2008 21:46:01 -0000 Received: (qmail 20892 invoked by uid 22791); 6 Jul 2008 21:46:00 -0000 X-Spam-Status: No, hits=-2.4 required=5.0 tests=AWL,BAYES_00,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/0.31) with ESMTP; Sun, 06 Jul 2008 21:45:38 +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 m66LeQDZ001032; Sun, 6 Jul 2008 17:40:26 -0400 Received: from pobox-3.corp.redhat.com (pobox-3.corp.redhat.com [10.11.255.67]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id m66LeQQp018030; Sun, 6 Jul 2008 17:40:26 -0400 Received: from touchme.toronto.redhat.com (IDENT:postfix@touchme.yyz.redhat.com [10.15.16.9]) by pobox-3.corp.redhat.com (8.13.1/8.13.1) with ESMTP id m66LdrDC013413; Sun, 6 Jul 2008 17:40:26 -0400 Received: from ton.toronto.redhat.com (ton.yyz.redhat.com [10.15.16.15]) by touchme.toronto.redhat.com (Postfix) with ESMTP id 1726D8001FF; Sun, 6 Jul 2008 17:39:36 -0400 (EDT) Received: from ton.toronto.redhat.com (localhost.localdomain [127.0.0.1]) by ton.toronto.redhat.com (8.13.1/8.13.1) with ESMTP id m66LdKk7002873; Sun, 6 Jul 2008 17:39:20 -0400 Received: (from fche@localhost) by ton.toronto.redhat.com (8.13.1/8.13.1/Submit) id m66LdKlr002872; Sun, 6 Jul 2008 17:39:20 -0400 Date: Sun, 06 Jul 2008 21:46:00 -0000 From: "Frank Ch. Eigler" To: Evgeniy Polyakov Cc: Christoph Hellwig , systemtap@sources.redhat.com Subject: Re: [Ksummit-2008-discuss] DTrace Message-ID: <20080706213920.GA1936@redhat.com> References: <20080628072605.GA505@in.ibm.com> <20080629084002.GA24131@lst.de> <20080630051034.GA4970@in.ibm.com> <20080630112913.GA18817@lst.de> <20080630171246.GB21660@redhat.com> <20080706123414.GA9265@lst.de> <20080706154612.GL2881@redhat.com> <20080706163533.GA16721@2ka.mipt.ru> <20080706182307.GA29895@2ka.mipt.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080706182307.GA29895@2ka.mipt.ru> User-Agent: Mutt/1.4.1i X-Scanned-By: MIMEDefang 2.58 on 172.16.52.254 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: 2008-q3/txt/msg00058.txt.bz2 Hi - On Sun, Jul 06, 2008 at 10:23:08PM +0400, Evgeniy Polyakov wrote: > > Yes, well, it turns out that the number of systemtap-specific kernel > > interfaces we have requested is ... precisely ... zero. > > Well, in the mail you replied to there was objection to add new > interfaces. That just illustrates the imperfect information floating around. > > We have on occasion asked that some established module interfaces > > simply not be *unexported*, but almost all of those requests have been > > turned down, requiring us to kludge. [...] > > Unexporting some things allows to change them in order to fix some bugs, > create better abstraction, introduce new feature... Having all calls > forever does not provide any gain to the kernel, instead project can be > pushed into the kernel, so anyone would win. OK, so you think systemtap should go into the kernel ... > > Think about how a non-intrusive system-wide probing must work, > > [...] It seems only kernel-side code can do all of that. Do you > > have a better suggestion? > Hmmm... Utrace suddenly stopped to work? (I assume you know that utrace is a kernel-side API. You may realize is that we are using it (via another layered module uprobes) to place probes into user-space programs.) > Even ptrace will work in described cases, if requested data is > accessible from userspace. [...] ... but now systemtap stay out to userspace? I don't understand. > And is it really much simpler to use dtrace scripts [...] for that? Simpler than what? A userspace debugger that messes with thread state? > (btw, does systemtap has the same complexity of script writing? If you point out an example of what you consider a complex dtrace script, I can try to answer that. - FChE