From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 17755 invoked by alias); 30 Jun 2008 17:14:25 -0000 Received: (qmail 17748 invoked by uid 22791); 30 Jun 2008 17:14:24 -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; Mon, 30 Jun 2008 17:14:03 +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 m5UHE1vr006226; Mon, 30 Jun 2008 13:14:01 -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 m5UHE1F6005293; Mon, 30 Jun 2008 13:14:01 -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 m5UHDJR3001967; Mon, 30 Jun 2008 13:13:52 -0400 Received: from ton.toronto.redhat.com (ton.yyz.redhat.com [10.15.16.15]) by touchme.toronto.redhat.com (Postfix) with ESMTP id 7374A8001FF; Mon, 30 Jun 2008 13:13:03 -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 m5UHClNw031590; Mon, 30 Jun 2008 13:12:47 -0400 Received: (from fche@localhost) by ton.toronto.redhat.com (8.13.1/8.13.1/Submit) id m5UHCkgN031589; Mon, 30 Jun 2008 13:12:46 -0400 Date: Mon, 30 Jun 2008 19:27:00 -0000 From: "Frank Ch. Eigler" To: Christoph Hellwig Cc: ksummit-2008-discuss@lists.linux-foundation.org, systemtap@sources.redhat.com, utrace-devel@redhat.com Subject: Re: [Ksummit-2008-discuss] DTrace Message-ID: <20080630171246.GB21660@redhat.com> References: <20080627150424.GB14894@parisc-linux.org> <1214580213.3394.40.camel@localhost.localdomain> <20080627155018.GC14894@parisc-linux.org> <1214583502.7698.15.camel@weaponx> <20080627163056.GB1416@lst.de> <20080628072605.GA505@in.ibm.com> <20080629084002.GA24131@lst.de> <20080630051034.GA4970@in.ibm.com> <20080630112913.GA18817@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080630112913.GA18817@lst.de> 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-q2/txt/msg00801.txt.bz2 Hi - On Mon, Jun 30, 2008 at 01:29:13PM +0200, Christoph Hellwig wrote: > [...] This might be getting a little offtopic for the kernel summit > discuss list, but let's start anyway, we can move this to a better > suited list, although I can't think of one except for linux-kernel. systemtap@sources.redhat.com utrace-devel@redhat.com > I'm not sure if that's the current design, but I can't find any > evidence in the code that it allows running handlers in process > context, all that's available is a kernel callback. [...] For systemtap's purposes, that is sufficient. Our probes are meant to run non-intrusively (they do not mess with user thread scheduling, their VM state, strictly limited time & space consumption), so actually injecting equivalent snippets of code into userspace for execution there does not seem to buy anything. Plus, like dtrace, we want scripts to be able to intermix probes (=> share data) amongst kernel and multiple user-space threads, and this seems most naturally done by running the probes themselves in kernel space. > [...] What we really need is a userspace interface so that it > actually can be used by thing like frysk or an implementation of the > userspace dtrace hooks. That will get built as other tools require it. Systemtap per se will likely not. > [...] For complex traces doing this in userspace is for sure a better idea. Can you elaborate upon this more complex scenario? - FChE