From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756584Ab0IGMJT (ORCPT ); Tue, 7 Sep 2010 08:09:19 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:60779 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756515Ab0IGMJO (ORCPT ); Tue, 7 Sep 2010 08:09:14 -0400 Date: Tue, 7 Sep 2010 17:32:58 +0530 From: Srikar Dronamraju To: Christoph Hellwig Cc: Peter Zijlstra , Ingo Molnar , Steven Rostedt , Arnaldo Carvalho de Melo , Linus Torvalds , Masami Hiramatsu , Oleg Nesterov , Mark Wielaard , Mathieu Desnoyers , Andrew Morton , Naren A Devaiah , Jim Keniston , Frederic Weisbecker , "Frank Ch. Eigler" , Ananth N Mavinakayanahalli , LKML , "Paul E. McKenney" , Srivatsa Vaddagiri Subject: Re: [PATCHv11 2.6.36-rc2-tip 5/15] 5: uprobes: Uprobes (un)registration and exception handling. Message-ID: <20100907120258.GK14891@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <20100825134117.5447.55209.sendpatchset@localhost6.localdomain6> <20100825134224.5447.89998.sendpatchset@localhost6.localdomain6> <1283377414.2059.1729.camel@laptop> <20100903164219.GB1904@linux.vnet.ibm.com> <1283534349.2050.297.camel@laptop> <20100906174642.GG14891@linux.vnet.ibm.com> <20100906204042.GA19815@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20100906204042.GA19815@infradead.org> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Mon, Sep 06, 2010 at 11:16:42PM +0530, Srikar Dronamraju wrote: > > > You don't have to, but you can. The problem I have with this stuff is > > > that it makes the pid thing a primary interface, whereas it should be > > > one of many filter possibilities. > > > > I think the otherway, > > Why instrument a process and filter it out, if we are not interested in it. > > While instrumenting kernel, we dont have this flexibility. So > > having a pid based filter is the right thing to do for kernel > > based tracing. > > > > If we can get the per process based tracing right, we can build > > higher lever stuff including the file based tracing easily. > > > > All tools/debuggers in the past have all worked with process based > > tracing. > > I have the feeling that you guys are at least partially talking past > each other. > > For the "perf probe --add" interface the only sane interface is one by > filename and then symbol / liner number / etc. Agree, probing by file name is a requirement and I am working towards that end. > > But that is just the interface - these probes don't nessecarily have to > be armed and cause global overhead once they are define. If the > implenmentation is smart enough it will defer arming the probe until > we actually use it, and that will be per-process quite often. Agree, That why I am trying to build file-based probing on pid-based probing. > > Which btw, brings up two more issues, one in uprobes and one in perf. > For one even in userspace I think the dynamic probes will really just > be the tip of the iceberg and we'll get more bang for the buck from > static traces, which is something that's no supported in uprobes yet. > As a start supporting the dtrace-style sdt.h header would be a great > help, and then we can decide if we need somthing even better on top. Yes, Static tracing using dtrace style sdt.h is a cool thing to do. Already SystemTap has this facility. However I think its probably better done at perf user interface level. The way I look at it is perf probe decodes the static markers and asks uprobes to place probepoints over there. Do you see a different approach? If yes can you tell what you were looking at? -- Thanks and Regards Srikar