From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 26075 invoked by alias); 30 Jul 2009 07:54:35 -0000 Received: (qmail 26064 invoked by uid 22791); 30 Jul 2009 07:54:34 -0000 X-SWARE-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 mx2.redhat.com (HELO mx2.redhat.com) (66.187.237.31) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 30 Jul 2009 07:54:27 +0000 Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id n6U7qO5X017968; Thu, 30 Jul 2009 03:52:25 -0400 Received: from ns3.rdu.redhat.com (ns3.rdu.redhat.com [10.11.255.199]) by int-mx2.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n6U7qNdA003465; Thu, 30 Jul 2009 03:52:24 -0400 Received: from host0.dyn.jankratochvil.net (sebastian-int.corp.redhat.com [172.16.52.221]) by ns3.rdu.redhat.com (8.13.8/8.13.8) with ESMTP id n6U7qMkK017902; Thu, 30 Jul 2009 03:52:23 -0400 Received: from host0.dyn.jankratochvil.net (localhost [127.0.0.1]) by host0.dyn.jankratochvil.net (8.14.3/8.14.3) with ESMTP id n6U7qLmp014936; Thu, 30 Jul 2009 09:52:21 +0200 Received: (from jkratoch@localhost) by host0.dyn.jankratochvil.net (8.14.3/8.14.3/Submit) id n6U7qKoM014934; Thu, 30 Jul 2009 09:52:20 +0200 Date: Thu, 30 Jul 2009 14:00:00 -0000 From: Jan Kratochvil To: Vladimir Prus Cc: Tom Tromey , gdb-patches@sourceware.org Subject: Re: [patch 0/4] varobj_list replacement [Re: [patch 4/8] Types GC [varobj_list to all_root_varobjs]] Message-ID: <20090730075220.GA14542@host0.dyn.jankratochvil.net> References: <20090525080233.GD13323@host0.dyn.jankratochvil.net> <20090710201104.GA7014@host0.dyn.jankratochvil.net> <200907301045.51541.vladimir@codesourcery.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200907301045.51541.vladimir@codesourcery.com> User-Agent: Mutt/1.5.19 (2009-01-05) X-IsSubscribed: yes Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2009-07/txt/msg00737.txt.bz2 On Thu, 30 Jul 2009 08:45:51 +0200, Vladimir Prus wrote: > On Wednesday 29 July 2009 Tom Tromey wrote: > > I understand from other mail that this patch is a prerequisite to the > > type GC work. However, I don't understand in what way it is needed. I > > probably missed something... could you either explain it or tell me > > where to look? > > In fact, I'm lost the big picture as well. If we want to optimize uninstall_variable, > then the 4/4 patch appears to be the simplest one that does the trick. However, if > that's a part of some bigger story, I'd be interested to understand it. The bigger story is: ------------------------------------------------------------------------------ The former Types GC code had to traverse varobj leaves (not just roots as does current varobj_list()). As I found the current varobj_list() calling convention is IMO-inconvenient and calling convention of the 'roots' and 'all' iterators/enumerators of varobjs should be the same I did not want to write a new function using the IMO-inconvenient calling convention. The new function was called all_varobjs() in the obsoleted patch: [patch 8/8] Types GC [varobj] http://sourceware.org/ml/gdb-patches/2009-05/msg00551.html So I rather IMO-fixed the calling convention of varobj_list() first so that the later 'all' varobjs iterator can already use the new calling convention while keeping the calling convention of the 'roots' and 'all' iterators the same. I found the new all_root_varobjs() iterator - patch 3/4 - to be clearly a win over current varobj_list() - no matter how insignificant change it may be - that just nobody so far has spent the time doing such code cleanup. The patches 1/4, 2/4 and 4/4 were later created just to support accepting the patch 3/4 and I probably would not submit 3/4 if I could imagine any problems getting it accepted. Moreover the Types GC changed from the former reference-counting to the current mark-and-sweep where maybe the leaves traversal is no longer needed. I have to check it more. speculation: IIRC it should have been fixing one objfile-invalidating bug where varobj leaf is using a different objfile due to TYPE_STUB referencing. But it is a bug out of the critical path for Types GC. In fact I do not like 1/4 or 2/4 to be accepted, they were created just to get 3/4 accepted. Also I do not think the 4/4 performance improvement is worth the reviewing time, it was also created just to get 3/4 accepted. ------------------------------------------------------------------------------ As I see 3/4 is not considered as a clear cleanup win. Understood it as rejected and I will be basing the next patches on the current varobj_list() calling convention as the preferred one. Thanks, Jan