From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 18625 invoked by alias); 13 May 2014 18:22:36 -0000 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 Received: (qmail 18611 invoked by uid 89); 13 May 2014 18:22:35 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.4 required=5.0 tests=AWL,BAYES_00,RP_MATCHES_RCVD autolearn=ham version=3.3.2 X-HELO: albireo.enyo.de Received: from albireo.enyo.de (HELO albireo.enyo.de) (46.237.207.196) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-SHA encrypted) ESMTPS; Tue, 13 May 2014 18:22:33 +0000 Received: from [172.17.203.2] (helo=deneb.enyo.de) by albireo.enyo.de with esmtps (TLS1.2:DHE_RSA_AES_128_CBC_SHA1:128) id 1WkHLN-0001a2-Pg; Tue, 13 May 2014 20:22:25 +0200 Received: from fw by deneb.enyo.de with local (Exim 4.80) (envelope-from ) id 1WkHLN-0005J5-Hs; Tue, 13 May 2014 20:22:25 +0200 From: Florian Weimer To: Gary Benson Cc: Mark Kettenis , gdb-patches@sourceware.org Subject: Re: [PATCH 0/2] Demangler crash handler References: <20140509100656.GA4760@blade.nx> <201405091120.s49BKO1f010622@glazunov.sibelius.xs4all.nl> <87fvkhjqvs.fsf@mid.deneb.enyo.de> <20140513102223.GC17805@blade.nx> Date: Tue, 13 May 2014 18:22:00 -0000 In-Reply-To: <20140513102223.GC17805@blade.nx> (Gary Benson's message of "Tue, 13 May 2014 11:22:23 +0100") Message-ID: <87ppjhilni.fsf@mid.deneb.enyo.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-IsSubscribed: yes X-SW-Source: 2014-05/txt/msg00168.txt.bz2 * Gary Benson: >> It would be more reliable to run the demangler in a separate >> process. > > Agreed. There are two issues though. First is performance: > GDB can demangle a lot of symbols--starting GDB on LibreOffice > demangles more than 369,000 symbols on my machine, and typing > "b " demangles 2,740,000 more--so the IPC overhead > has to be seriously low. Is most of the demangling of the bulk kind? These cases are easy in the sense that a ping-pong between the two processes is avoidable. More worrisome would be the occasional demangling as part of other tasks, where the context switches might become very visible. >> What's so difficult about fixing the demangler? > > It's not so difficult really, but fixes take time to diagnose, > reproduce, fix, test, review, etc. I was referring to a more permanent fix, not just patching the bug of the day as users encounter it. > During that interval the user cannot use GDB to debug their program. > This patch is about allowing the user the possibility of getting > their work done. I suppose I could run the demangler on all symbols in Fedora and downstream and see what breaks. Would that help?