From owner-freebsd-current@FreeBSD.ORG Tue Sep 16 03:35:02 2008 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id BA1A6106566B for ; Tue, 16 Sep 2008 03:35:02 +0000 (UTC) (envelope-from sgk@troutmask.apl.washington.edu) Received: from troutmask.apl.washington.edu (troutmask.apl.washington.edu [128.208.78.105]) by mx1.freebsd.org (Postfix) with ESMTP id 999C88FC0C for ; Tue, 16 Sep 2008 03:35:02 +0000 (UTC) (envelope-from sgk@troutmask.apl.washington.edu) Received: from troutmask.apl.washington.edu (localhost.apl.washington.edu [127.0.0.1]) by troutmask.apl.washington.edu (8.14.3/8.14.3) with ESMTP id m8G3YxkC031414; Mon, 15 Sep 2008 20:34:59 -0700 (PDT) (envelope-from sgk@troutmask.apl.washington.edu) Received: (from sgk@localhost) by troutmask.apl.washington.edu (8.14.3/8.14.3/Submit) id m8G3YxvD031413; Mon, 15 Sep 2008 20:34:59 -0700 (PDT) (envelope-from sgk) Date: Mon, 15 Sep 2008 20:34:59 -0700 From: Steve Kargl To: Stephen Montgomery-Smith Message-ID: <20080916033459.GA31220@troutmask.apl.washington.edu> References: <48CDBC78.4010409@math.missouri.edu> <20080915195021.GA69528@cons.org> <48CEFF74.8020602@math.missouri.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <48CEFF74.8020602@math.missouri.edu> User-Agent: Mutt/1.4.2.3i Cc: Martin Cracauer , freebsd-current@freebsd.org Subject: Re: Improved multiprocessor usage on amd64 X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 16 Sep 2008 03:35:02 -0000 On Mon, Sep 15, 2008 at 07:36:04PM -0500, Stephen Montgomery-Smith wrote: > > ... and each thread is a loop of the form > > while (1) { > wait until told to start; > do massive amounts of floating point arithmetic (only additions and > multiplications) on large arrays; > tell the master process that you are done; > } > > >Do you have about as many threads as processor or more? > > Both ways. The time difference between the two approaches is negligible. > Are you using ULE? With my MPI applications, if the number of launched processes exceeds the number of cpus by 1, ULE falls through the floor. I have a nagging feeling that there is a problem with cpu affinity. http://lists.freebsd.org/pipermail/freebsd-current/2008-July/086917.html -- Steve