Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com Delivered-To: mailing list cygwin AT cygwin DOT com Date: Sun, 6 Feb 2005 13:08:24 -0500 From: Christopher Faylor To: cygwin AT cygwin DOT com Subject: hyperthreading fix, try #1 Message-ID: <20050206180824.GA32126@trixie.casa.cgf.cx> Reply-To: cygwin AT cygwin DOT com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.1i I have a system set up now so, last week, in between real work fire drills and the sourceware.org emergency, I tried running a couple of the scripts that were advertised as causing problems. Well, whaddaya know? I got a hang and/or "other weird behavior". After checking backtraces on a couple of processes, it became clear that the pipe handling was the culprit, which was my suspicion. I thought it would turn out to be either a problem with the way interrupting pipe I/O was handled or with a race in the signal handling notification. I was desperately hoping that it wouldn't be the latter since that is very hard to debug. Anyway, I took a look at the pipe handling code for the 457th time and this time I saw a couple of obvious flaws in my logic. The synchronization was all off. Fixing that seems to have fixed my hyperthreading problems. I have run three invocations of the scripts for four days without a hiccup. Previously, I had problems within minutes. I'm not naive enough to think that I've solved all of the hyperthreading problems but I would like people to try today's snapshot (or any snapshot newer than today's) and report on whether it solves the problem or not. If it doesn't, please provide as simple a test case as possible so that I can duplicate the problem. While, it is ok to report that your 23 hour build fails mysteriously, I don't anticipate that I will be able to do much to help those kinds of cases. That's why a test case is crucial. I'm not particularly interested in reports about non-hyperthreading systems unless you can show a regression between this snapshot and previous releases. cgf -- 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/