From owner-freebsd-stable@FreeBSD.ORG Mon Apr 12 23:18:39 2010 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 373151065673 for ; Mon, 12 Apr 2010 23:18:39 +0000 (UTC) (envelope-from bms@incunabulum.net) Received: from out2.smtp.messagingengine.com (out2.smtp.messagingengine.com [66.111.4.26]) by mx1.freebsd.org (Postfix) with ESMTP id 038988FC3A for ; Mon, 12 Apr 2010 23:18:38 +0000 (UTC) Received: from compute1.internal (compute1.internal [10.202.2.41]) by gateway1.messagingengine.com (Postfix) with ESMTP id 6FDB8EB92A; Mon, 12 Apr 2010 19:18:38 -0400 (EDT) Received: from heartbeat1.messagingengine.com ([10.202.2.160]) by compute1.internal (MEProxy); Mon, 12 Apr 2010 19:18:38 -0400 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=messagingengine.com; h=message-id:date:from:mime-version:to:subject:references:in-reply-to:content-type:content-transfer-encoding; s=smtpout; bh=ziUNcZbqsNpYJTHBZWUg+G2lvB4=; b=Urjxtf4lrx0Pqts86LinL5HF4JGmeL/Wy9hEQ+oHvDBKgbjbS3n552yfhfGbfcG14OfMrksAf3XG10YiztoktrhviRMCjwNKE69gXXwCnQCxs9sTCHR6aed4Ihh9/7JtPmleytTqV6ZxNq/tiWBDu7/cnuugaM5BTFrFe+po9k0= X-Sasl-enc: ApQxToZa9+H+G2Fkdqw00WEWxFnDqK3Zx0QUCcxf7ozH 1271114318 Received: from anglepoise.lon.incunabulum.net (cpc2-dals7-0-0-cust253.hari.cable.virginmedia.com [82.35.112.254]) by mail.messagingengine.com (Postfix) with ESMTPSA id ED0EA4C2043; Mon, 12 Apr 2010 19:18:37 -0400 (EDT) Message-ID: <4BC3AA4C.30904@incunabulum.net> Date: Tue, 13 Apr 2010 00:18:36 +0100 From: Bruce Simpson User-Agent: Mozilla/5.0 (X11; U; FreeBSD amd64; en-US; rv:1.9.1.9) Gecko/20100406 Thunderbird/3.0.4 MIME-Version: 1.0 To: Jeremy Chadwick , freebsd-stable References: <20100412.131213.4959786962516027.chat95@mac.com> <4BC3311F.5060503@icyb.net.ua> <20100412150023.GA80292@icarus.home.lan> In-Reply-To: <20100412150023.GA80292@icarus.home.lan> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Subject: Re: Only 70% of theoretical peak performance on FreeBSD 8/amd64, Corei7 920 X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 12 Apr 2010 23:18:39 -0000 Hi all, There's a port archivers/pbzip2, and I am inclined to believe this is a good benchmark for multi-core performance in real-world usage (with an appropriate input data set). BZIP2 is a compression algorithm which is readily applicable to multicore, because of the nature in which its workload may be partioned amongst multiple CPU cores. It block-sorts, and it can compress long runs of input data independently of other CPU threads. When I used PBZIP2 informally back in January, before advising on FreeBSD/Xen, I saw largely the results I'd expect to see from such a workload, and didn't encounter pessimization of benchmark figures. Informal tests were performed on 8-STABLE at that time. The OP may well be looking for Newton-Raphson approximations, to the derivatives involved in his friend's linear algebra system. The point is that PBZIP2 would also exercise context switches in a real-life workload. I'd be concerned, as anyone else would be, about benchmarks which apparently challenge FreeBSD's ability to tackle significant mathematical workloads. But from what little I understand, from speaking to David Schultz and others who have been involved with FreeBSD's floating point performance, on a scientific basis -- without a scientifically reproducible experiment, I don't see a problem. Obviously, I am concerned that Nakata-san observes what he regards to be a problem, and would like to help any way I can. cheers, BMS