Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm 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 Date: Mon, 17 Nov 2003 12:25:49 +0100 From: Corinna Vinschen To: newlib@sources.redhat.com Cc: Wayne Hayes , cygwin@cygwin.com Subject: [wayne@cs.toronto.edu: Cygwin-1.5.5 sscanf on floats: 20 times slower than 2 years ago] Message-ID: <20031117112549.GF18706@cygbert.vinschen.de> Reply-To: newlib@sources.redhat.com Mail-Followup-To: newlib@sources.redhat.com, Wayne Hayes , cygwin@cygwin.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.1i Since scanf and the floating point arithmetic is implemented in newlib, I've redirected this message there. Does anybody have an idea, what could slow down float scanning in sscanf by a factor of 20? Corinna ----- Forwarded message from Wayne Hayes ----- > Date: Sun, 16 Nov 2003 09:54:31 -0500 > From: Wayne Hayes > Subject: Cygwin-1.5.5 sscanf on floats: 20 times slower than 2 years ago > To: cygwin@cygwin.com > > Hello. Until recently I was running W2k with an ancient version of > cygwin; I don't know what version it was, but if anybody cares I've > put a copy of cygwin1.dll (dated 2001-May-20) at > > http://www.cs.toronto.edu/~wayne/tmp/cygwin1-old.dll.gz > > It worked fine on W2k for the past 2.5 years. > > I recently upgraded to Windows XP and this old cygwin stopped working. > No problem, I say, it's also time to upgrade cygwin, so I go install the > most recent version. > > Everything works fine, except one of my I/O intensive simulations starts > running about 20 times slower! > > After copious mucking about, I finally narrowed it down to sscanf: sscanf > on double precisions numbers, such as > > double a; > char line [80]; > fgets(line...) > sscanf(line, "%lf", &a); > > runs about 20 times slower than in the old cygwin. Replacing the sscanf > with a call to atof gets back the old speed. It's only noticable, of > course, if you're scanning a huge file. In my case, it's a 60MB file > that contains tens of thousands of lines of ASCII floating point numbers. > > So, consider this a bug report. A slowdown of a factor of 20 is not really > a good thing. > > The output of "cygcheck -s -v -r > cygcheck.out" can be found at > > http://www.cs.toronto.edu/~wayne/tmp/cygcheck-XP-1.5.5.out.gz > > Thanks! > > - Wayne ----- End forwarded message ----- -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Developer mailto:cygwin@cygwin.com Red Hat, Inc. -- 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/