From owner-freebsd-stable@FreeBSD.ORG Tue Apr 13 05:30:10 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 7A544106564A for ; Tue, 13 Apr 2010 05:30:10 +0000 (UTC) (envelope-from alan.l.cox@gmail.com) Received: from mail-pz0-f201.google.com (mail-pz0-f201.google.com [209.85.222.201]) by mx1.freebsd.org (Postfix) with ESMTP id 4A61A8FC1F for ; Tue, 13 Apr 2010 05:30:10 +0000 (UTC) Received: by pzk39 with SMTP id 39so399827pzk.7 for ; Mon, 12 Apr 2010 22:30:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:reply-to:in-reply-to :references:date:received:message-id:subject:from:to:cc:content-type; bh=MrFyFAVemtoe1ZtEvMvvwaCcG0/7ti54Lz6kL1JfjQA=; b=W1TZ9Fpt1xaNk8lTskZA7v+Y9Qh6ifnT5vrDuBRXjzRSRyQiCF1gh4r30BkzrqBIc0 7y0ZBkxOakR2KWBPFHv/wXVO73Yum7yQq6y5GPukdpz4sUUTywCQCdvLWmBwpUukvyZz X5hPZqmSMUfG3ERQ1l2fF0n0Gc5Umw7bVAKsU= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:reply-to:in-reply-to:references:date:message-id :subject:from:to:cc:content-type; b=taCH79ezpsxEe3uYYvd35mBfKLrQF+PmKWNND1Mtf+Iwh4nKorG9AgxLl8bO6bUxap VKyhdgzOSb4SJ8z87NpRohzqqrqRN+hmMLOzy9XYgjbOCRAYUWoB+QTcPT3cccFAyQRC CkgBzaFCfvT0HQc09d/BY4zM2uY3zp46CYPA0= MIME-Version: 1.0 Received: by 10.143.158.20 with HTTP; Mon, 12 Apr 2010 22:30:09 -0700 (PDT) In-Reply-To: <20100412.131213.4959786962516027.chat95@mac.com> References: <20100412.131213.4959786962516027.chat95@mac.com> Date: Tue, 13 Apr 2010 00:30:09 -0500 Received: by 10.142.152.5 with SMTP id z5mr2173827wfd.266.1271136609546; Mon, 12 Apr 2010 22:30:09 -0700 (PDT) Message-ID: From: Alan Cox To: Maho NAKATA Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: 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 Reply-To: alc@freebsd.org List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 13 Apr 2010 05:30:10 -0000 On Sun, Apr 11, 2010 at 11:12 PM, 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 amd64 > using dgemm > (a linear algebra routine, matrix-matrix multiplication). > I obtained only 70% of theoretical peak performance on FreeBSD 8/amd64 and > almost 95% on Ubuntu 9.10 /amd64. I'm really disappointed. > > *Introduction* > I'm a friend of Gotoh Kazushige, the principal developers of GotoBLAS. He > 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 > still not very will > > sophisticated, but on *BSDs, its worst; they uses too fine memory > allocation method, > > so we cannot expect large continuous physical memory allocation. > These statements about FreeBSD's memory management are wrong, or at least outdated. FreeBSD is very likely to allocate physical memory in contiguous chunks to your memory-hungry application even if automatic superpage promotion does not occur. You should refer your friend to my paper at http://www.usenix.org/events/osdi02/tech/full_papers/navarro/navarro_html/and tell him that FreeBSD >= 7.2 implements a variation on what that paper describes. Regards, Alan