From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 10719 invoked by alias); 10 Nov 2003 21:54:06 -0000 Mailing-List: contact gdb-patches-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sources.redhat.com Received: (qmail 9958 invoked from network); 10 Nov 2003 21:54:03 -0000 Received: from unknown (HELO palrel11.hp.com) (156.153.255.246) by sources.redhat.com with SMTP; 10 Nov 2003 21:54:03 -0000 Received: from hplms2.hpl.hp.com (hplms2.hpl.hp.com [15.0.152.33]) by palrel11.hp.com (Postfix) with ESMTP id 4F5481C0689A; Mon, 10 Nov 2003 13:54:03 -0800 (PST) Received: from napali.hpl.hp.com (napali.hpl.hp.com [15.4.89.123]) by hplms2.hpl.hp.com (8.12.10/8.12.10/HPL-PA Hub) with ESMTP id hAALrrxf022593; Mon, 10 Nov 2003 13:54:02 -0800 (PST) Received: from napali.hpl.hp.com (napali [127.0.0.1]) by napali.hpl.hp.com (8.12.3/8.12.3/Debian-6.6) with ESMTP id hAALrnFO018632; Mon, 10 Nov 2003 13:53:49 -0800 Received: (from davidm@localhost) by napali.hpl.hp.com (8.12.3/8.12.3/Debian-6.6) id hAALrXnx018628; Mon, 10 Nov 2003 13:53:33 -0800 From: David Mosberger MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16304.2269.815957.953193@napali.hpl.hp.com> Date: Mon, 10 Nov 2003 21:54:00 -0000 To: Marcel Moolenaar Cc: davidm@hpl.hp.com, Andrew Cagney , "J. Johnston" , gdb-patches@sources.redhat.com, Kevin Buettner Subject: Re: RFA: ia64 portion of libunwind patch In-Reply-To: <20031109013421.GA742@athlon.pn.xcllnt.net> References: <3FA2B71A.3080905@redhat.com> <3FA2CA1B.7000502@redhat.com> <16290.59502.799536.383397@napali.hpl.hp.com> <3FAC12D3.2070207@redhat.com> <16300.8192.489647.740612@napali.hpl.hp.com> <3FAC2454.2030009@redhat.com> <16300.9949.513264.716812@napali.hpl.hp.com> <20031109013421.GA742@athlon.pn.xcllnt.net> Reply-To: davidm@hpl.hp.com X-URL: http://www.hpl.hp.com/personal/David_Mosberger/ X-SW-Source: 2003-11/txt/msg00197.txt.bz2 >>>>> On Sat, 8 Nov 2003 17:34:21 -0800, Marcel Moolenaar said: Marcel> On Fri, Nov 07, 2003 at 03:12:29PM -0800, David Mosberger wrote: >> >>>>> On Fri, 07 Nov 2003 18:01:40 -0500, Andrew Cagney said: Andrew> Is fetching the table elements via a function, rather than a Andrew> direct access, really that significant an overhead? >> Is allocating a scratch buffer in gdb really such a big issue? >> It's very late for proposing libunwind API changes. Marcel> I think it's very early to have it nailed down. No, the static code part of libunwind is not really open to non-backwards-compatible changes anymore. Things are slightly different for the dynamic code support, but the static part has too many users already for making code-breaking changes. Also, backwards-compatible changes are of course much easier to add. Marcel> Despite ones efforts to create a clean system, there are Marcel> always assumptions underlying the code, including the API. I Marcel> think it's in the best interest of libunwind if the Marcel> developers (yes, you David :-) remain sensitive and open Marcel> minded about the how well libunwind interfaces with or Marcel> integrates into code that has a need for unwinding. It's not a good idea to make broad conclusions based on one particular issue. In this case, the issue appears to be entirely theoretical (nobody has produced any numbers showing that, in a realistic scenario, the current scheme makes, say, gdb startup X% slower, with X being some large number). Unless somebody produces such numbers, I'm certainly not going to change the API in a non-backwards-compatible fashion. Perhaps we can find a backwards-compatible way of doing this, in which case it's _much_ easier to add the feature. Also, please keep in mind that libunwind is an open-source project. If you don't like something, or think a feature is missing, submit a clean patch. --david