X-Recipient: archive-cygwin@delorie.com X-SWARE-Spam-Status: No, hits=-2.4 required=5.0 tests=AWL,BAYES_00,SPF_PASS X-Spam-Check-By: sourceware.org Message-ID: <4AF6E91C.1090508@bmts.com> Date: Sun, 08 Nov 2009 10:51:56 -0500 From: Ralph Hempel User-Agent: Thunderbird 2.0.0.6 (X11/20071022) MIME-Version: 1.0 To: cygwin@cygwin.com, cygwin@cygwin.com Subject: Re: Broken autoconf mmap test (was Re: 1.7] BUG - GREP slows to a crawl with large number of matches on a single file) References: <20091108141548.GB26344@calimero.vinschen.de> In-Reply-To: <20091108141548.GB26344@calimero.vinschen.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-brucetelecom.com-MailScanner-Information: Please contact Bruce Telecom 519.368.2000 for more information X-brucetelecom.com-MailScanner: Found to be clean X-brucetelecom.com-MailScanner-From: rhempel@bmts.com X-IsSubscribed: yes Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Delivered-To: mailing list cygwin@cygwin.com Corinna Vinschen wrote: > On Nov 8 14:56, Corinna Vinschen wrote: >> Btw., the check for mmap in grep's configure file is broken. It tries >> to mmap to a fixed address formerly allocated via malloc(). This doesn't >> work on Windows. An autoconf run with a newer version of autoconf would >> be nice. > > I just found that the latest autoconf *still* has this broken test > for mmap, which basically calls > > data2 = malloc (size); > mmap(data2, ...); > > Why has this test never been fixed? Chuck? I can't answer that question but this thread points out very important lessons in debugging specifically and projects in general. 1. Easily reproducible test cases are critical to getting somone interested in fixing your problem. 2. Having the good fortune to have somebody run the test case and duplicate the problem helps a bit more. 3. Having that person challenge the assumptions under which the code has been working for YEARS without a complaint helps a bit more. 4. Having that person do a great analysis that shows why the problem exists helps even more. 5. Going even one step further and trying to figure out why the problem has existed for years and what else might be wrong is just the icing on the cake. Bravo Corinna - on a Sunday no less... Cheers, Ralph -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple