X-Spam-Check-By: sourceware.org Message-ID: <4420C321.8040606@pacific.net.sg> Date: Wed, 22 Mar 2006 11:23:13 +0800 From: Erich Dollansky User-Agent: Thunderbird 1.5 (X11/20060112) MIME-Version: 1.0 To: cygwin@cygwin.com Subject: Re: pthreads don't scale on windows xp, but does scale on linux, cygwin 1.5.19 References: <25082fe70603210232uc7e017ft8848c336a649c7dc@mail.gmail.com> <44200AD3.7000303@byu.net> <25082fe70603210714h23ec44d8v7f1cc9c0f2d4ad30@mail.gmail.com> <7.0.1.0.0.20060321073317.01dda4f8@weasel.com> <4420BDB9.1040105@myrealbox.com> <7.0.1.0.0.20060321190327.01d5def0@weasel.com> In-Reply-To: <7.0.1.0.0.20060321190327.01d5def0@weasel.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes 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 Hi, jdeifik wrote: > At 07:00 PM 3/21/2006, you wrote: > >> jdeifik wrote: >>> I have a dual xeon 2.4ghz machine with hypertreading enabled. >>> This gives me 4 logical processors. > I am not sure why it is important to have a HT aware scheduler for > Windows, when there are 4 or more > threads. I can see with 2 threads you would like to have one per > physical processor. > With 4 or more threads, cygwin phtreads really sucks, 4->62%, 6->39%, > 8->30% efficiency. I do not wonder. HT does not give a full CPU to the other thread. If the scheduler is not aware of the problem, it actually slows down the performance of the real CPU. > > It seems to me that more and more apps are turning to threading for > performance, > and more and more hardware is available with multi-processor, > multi-core, and multi-threading. Yes, this is why programs must be written to run with real CPUs and not something Intel calls HyperThreading. Erich -- 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/