X-Spam-Check-By: sourceware.org Date: Thu, 18 Jan 2007 10:14:00 +0100 From: Corinna Vinschen To: cygwin@cygwin.com Subject: Re: 1.7.0 CVS mmap failure Message-ID: <20070118091400.GC27843@calimero.vinschen.de> Reply-To: cygwin@cygwin.com Mail-Followup-To: cygwin@cygwin.com References: <20070105182234.GC12776@calimero.vinschen.de> <20070105192302.GD12776@calimero.vinschen.de> <20070110095345.GL23638@calimero.vinschen.de> <20070117103959.GA23172@calimero.vinschen.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.2i Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: 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 On Jan 17 13:42, Brian Ford wrote: > On Wed, 17 Jan 2007, Corinna Vinschen wrote: > > On Jan 16 17:28, Brian Ford wrote: > > > PS: In an strace of this, I see three fstat64s called from within a > > > single mmap64. Do you know where they all are, and if two should be > > > optimized away? > > > > There's only one such call in list::set. > > which is called from map::add_list, yes. I also see one in > map::get_list_by_fd. Uh, yes. > mmap.cc:1203 mmap64(): > map_list = mmapped_areas.get_list_by_fd (fd); > mmap.cc:982 mmap_worker(): > if (!(map_list = mmapped_areas.get_list_by_fd (fd)) > mmap.cc:983 mmap_worker(): > && !(map_list = mmapped_areas.add_list (fd))) > > Also: > > mmap.cc:1134 mmap64(): > DWORD low = GetFileSize (fh->get_handle (), &high); > > > STC? > > It looks like your statement is true for the first mmap in a process, but > subsequent mmaps have significant overhead. In the attached STC, I count > 5 fstat64s of the same fd via strace, plus the GetFileSize mentioned > above. > > PS. Since this isn't a bug, I don't expect you to do any more than > consider putting it in your long term low priority que or reply with a PTC > Thanks for the evaluation tuits ;-). Right, it's an optimization problem rather than a bug. Patches welcome, but I've put it on my TODO list, too. Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Project Co-Leader cygwin AT cygwin DOT com Red Hat -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/