From owner-freebsd-stable@FreeBSD.ORG Thu Apr 15 02:49:33 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 213D31065670; Thu, 15 Apr 2010 02:49:33 +0000 (UTC) (envelope-from yanefbsd@gmail.com) Received: from qw-out-2122.google.com (qw-out-2122.google.com [74.125.92.26]) by mx1.freebsd.org (Postfix) with ESMTP id B68B08FC15; Thu, 15 Apr 2010 02:49:32 +0000 (UTC) Received: by qw-out-2122.google.com with SMTP id 5so293313qwi.7 for ; Wed, 14 Apr 2010 19:49:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:received:message-id:subject:from:to:cc:content-type :content-transfer-encoding; bh=iAQ0TIkNIMUj0qnyfCih2O/V34BYszaqDaX/jh5ZOdI=; b=hiO6JLCoEhh3dkt5x1zOOLE+BIpfSrixV1H0K+dKYCHa2zZHODOkeYm3JjDEmcPRut 9Nh5uAWJxjrTbk8zWxgfbY3KAbjxqxgFuWTjl+cgjo0T5sEqazoPpmEENKMiquTJ+4Zd fzwTqwVMF+YZwvh26JBYegoyrdJ0zPatqEl2U= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=Stm1vIuXFvEK07UkuTscWmv1s2yXuvh4Pz/l15RDM7sjAIrukcjnnkmz8WY/CXmHSO f+in/yaqvROtSARnkH0kyqWXXT4nkiAdhar/YZY1Qo3Qdy1ZlcoIgdMnwzVNQfo6D+GU jK30v6RsVkrVrJVBp7GwPMojIiZLq6NI1mYUA= MIME-Version: 1.0 Received: by 10.229.28.85 with HTTP; Wed, 14 Apr 2010 19:49:19 -0700 (PDT) In-Reply-To: <20100415.094643.450985660335296086.chat95@mac.com> References: <20100414.082109.29593248145846106.chat95@mac.com> <4BC5DEB4.1090208@freebsd.org> <20100415.094643.450985660335296086.chat95@mac.com> Date: Wed, 14 Apr 2010 19:49:19 -0700 Received: by 10.229.213.77 with SMTP id gv13mr2549833qcb.63.1271299759481; Wed, 14 Apr 2010 19:49:19 -0700 (PDT) Message-ID: From: Garrett Cooper To: Maho NAKATA Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: amvandemore@gmail.com, freebsd-stable@freebsd.org, alc@freebsd.org, alan.l.cox@gmail.com, avg@freebsd.org, als@modulus.org Subject: Re: HyperThreading makes worse to me (was Re: How to reproduce: 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: Thu, 15 Apr 2010 02:49:33 -0000 On Wed, Apr 14, 2010 at 5:46 PM, Maho NAKATA wrote: > Hi Andry and Adam > > My test again. No desktop, etc. I just run dgemm. > Contrary to Adam's result, Hyper Threading makes the performance worse. > all tests are done on Core i7 920 @ 2.67GHz. (TurboBoost @2.8GHz) > > Turbo Boost off, Hyper threading off: 82% (35GFlops) =A0 =A0[1] > Turbo Boost off, Hyper threading off: 72% (30.5GFlops) =A0[2] > > Turbo Boost on, =A0Hyper threading on: 71% (32GFlops) =A0 =A0[3] > Turbo Boost off, Hyper threading off: 84-89% (38-40GFlops) [4] Doesn't this make sense? Hyperthreaded cores in Intel procs still provide an incomplete set of registers as they're logical processors, so I would expect for things to be slower if they're automatically run on the SMT cores instead of the physical ones. Is there a weighting scheme to SCHED_ULE where logical processors (like the SMT variety) get a lower score than real processors do, and thus get scheduled for less intensive interrupting tasks, or maybe just don't get scheduled in high use scenarios like it would if it was a physical processor? Thanks, -Garrett