From owner-freebsd-stable@FreeBSD.ORG Mon Apr 12 13:58:20 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 9F9B6106568C for ; Mon, 12 Apr 2010 13:58:20 +0000 (UTC) (envelope-from lists@mawer.org) Received: from mail-ew0-f224.google.com (mail-ew0-f224.google.com [209.85.219.224]) by mx1.freebsd.org (Postfix) with ESMTP id 132948FC2A for ; Mon, 12 Apr 2010 13:58:17 +0000 (UTC) Received: by ewy24 with SMTP id 24so939424ewy.33 for ; Mon, 12 Apr 2010 06:58:17 -0700 (PDT) MIME-Version: 1.0 Received: by 10.103.213.18 with HTTP; Mon, 12 Apr 2010 06:58:17 -0700 (PDT) In-Reply-To: References: <20100412.131213.4959786962516027.chat95@mac.com> Date: Mon, 12 Apr 2010 23:58:17 +1000 Received: by 10.102.165.11 with SMTP id n11mr2053986mue.23.1271080697064; Mon, 12 Apr 2010 06:58:17 -0700 (PDT) Message-ID: From: Antony Mawer To: Adrian Chadd Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: Maho NAKATA , freebsd-stable@freebsd.org 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 13:58:20 -0000 This may well be the same sort of issue that was discussed in this thread h= ere: http://lists.freebsd.org/pipermail/freebsd-hackers/2010-March/031004.ht= ml In short, the Core i7 CPUs have a feature called "TurboBoost" where the clock speed of one or more cores is boosted when other cores are idle and in a C2 or C3 sleep status ... if the appropriate power saving mode isn't active on the system (which I don't think FreeBSD does by default?), the idle cores are never put into the appropriate power saving state, and as a result TurboBoost never kicks in... It _may_ be that Ubuntu configures this correctly whereas FreeBSD does not (out of the box)? Of course it may be something else entirely, but worth checking out... --Antony On Mon, Apr 12, 2010 at 7:31 PM, Adrian Chadd wrote: > Of course, what would be helpful is actually figuring out what is > going on rather than some conjecture. :) > > With what he said, tweaking memory allocation under FreeBSD and/or > linux would change the performance characteristics and either validate > or disprove his assumptions? > > > Adrian > > On 12 April 2010 12:12, Maho NAKATA wrote: >> Hi FreeBSD developers, >> [the original article in Japanese can be found at >> http://blog.goo.ne.jp/nakatamaho/e/b5f6fbc3cc6e1ac4947463eb1ca4eb0a ] >> >> *Abstract* >> I compared the peak performance of FreeBSD 8.0/amd64 and Ubuntu 9.10 amd= 64 using dgemm >> (a linear algebra routine, matrix-matrix multiplication). >> I obtained only 70% of theoretical peak performance on FreeBSD 8/amd64 a= nd >> almost 95% on Ubuntu 9.10 /amd64. I'm really disappointed. >> >> *Introduction* >> I'm a friend of Gotoh Kazushige, the principal developers of GotoBLAS. H= e told me that >> FreeBSD is not suitable OS for scientific computing or high performance = computing. He says >> (in Japanese and my translation): >> >>> I guess FreeBSD does page coloring, but I don't think FreeBSD considers= very large cache >>> size which recent CPU has. Support of a very large cache on Linux is st= ill not very will >>> sophisticated, but on *BSDs, its worst; they uses too fine memory alloc= ation method, >>> so we cannot expect large continuous physical memory allocation. >>> Moreover, process scheduling is not so nice as *BSD employs an algorith= m that >>> changes physical CPUs in turn instead of allocating one core for such k= ind of jobs. >>> Take your own benchmark, and you'll see.. >> >> *Result* >> Machine: Core i7 920 (42.56-44.8Gflops) / DDR3 1066 >> OS: FreeBSD 8.0/amd64 and Ubuntu 9.10 >> GotoBLAS2: 1.13 >> >> dgemm result >> OS =A0 =A0 =A0: FLOPS =A0 =A0 =A0 =A0 =A0 : percent in peak >> FreeBSD : 32.0 GFlops =A0 =A0 : 71% >> Ubuntu =A0: 42.0-42.7GFlops : 93.8%-95.3% >> >> Thanks, >> -- Nakata Maho http://accc.riken.jp/maho/ , http://ja.openoffice.org/ >> =A0 Nakata Maho's PGP public keys: http://accc.riken.jp/maho/maho.pgp.tx= t >> >> >> >> >> _______________________________________________ >> freebsd-stable@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-stable >> To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org= " >> > _______________________________________________ > freebsd-stable@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org" >