From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 28839 invoked by alias); 23 May 2006 19:36:53 -0000 Received: (qmail 28788 invoked by uid 22791); 23 May 2006 19:36:53 -0000 X-Spam-Status: No, hits=-1.2 required=5.0 tests=AWL,BAYES_50,SPF_HELO_PASS X-Spam-Check-By: sourceware.org Received: from mail8.fw-sd.sony.com (HELO mail8.fw-sd.sony.com) (160.33.66.75) by sourceware.org (qpsmtpd/0.31) with ESMTP; Tue, 23 May 2006 19:36:50 +0000 Received: from mail3.sjc.in.sel.sony.com (mail3.sjc.in.sel.sony.com [43.134.1.211]) by mail8.fw-sd.sony.com (8.12.11/8.12.11) with ESMTP id k4NJamQL017102 for ; Tue, 23 May 2006 19:36:48 GMT Received: from [43.134.85.135] ([43.134.85.135]) by mail3.sjc.in.sel.sony.com (8.12.11/8.12.11) with ESMTP id k4NJam80008968 for ; Tue, 23 May 2006 19:36:48 GMT Message-ID: <44736450.7060601@am.sony.com> Date: Tue, 23 May 2006 19:36:00 -0000 From: Tim Bird User-Agent: Thunderbird 1.5 (X11/20051201) MIME-Version: 1.0 To: systemtap Subject: Random ideas about systemtap dependencies Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2006-q2/txt/msg00472.txt.bz2 As I've been thinking about the operation of SystemTap (as I understand it), I got to wondering about something. Please excuse this long-winded introduction... I maintain a system called KFT - Kernel Function Trace, which allows you to monitor the entry and exit of every kernel function. It does this by using GCC compiler flags to put callouts in the prolog and epilog of every function, at compile time. KFT can log all the functions, but in normal usage it filters by function duration and only shows those functions which take a long time to execute. (Finding long-duration functions is really it's primary purpose, although it can be used for other things.) However, KFT can also filter by function address, allowing you to only invoke the event handler when certain specified functions are entered and exited. Would it be theoretically possible to adapt SystemTap to use this as a method of monitoring function entry and exit, rather than using Kprobes? I ask because I think that some embedded platforms don't have Kprobe support, but every platform I know of supports the GCC compiler switches for instrumenting functions. Use of this would have lots of drawbacks, so I'm not recommending it. I'm just thinking out loud. Does SystemTap have any dependencies on other kernel features that are not available on all architectures? (Things like timers are architecture dependent, but a board will always have at least gettimeofday, though it may have cruddy resolution). Anyway, just an idle thought. -- Tim ============================= Tim Bird Architecture Group Chair, CE Linux Forum Senior Staff Engineer, Sony Electronics =============================