From owner-freebsd-stable@FreeBSD.ORG Thu Apr 15 02:50:26 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 B280D1065678; Thu, 15 Apr 2010 02:50:26 +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 511118FC19; Thu, 15 Apr 2010 02:50:26 +0000 (UTC) Received: by qw-out-2122.google.com with SMTP id 5so293477qwi.7 for ; Wed, 14 Apr 2010 19:50:25 -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=H1hyQ5I0VaPraXeizkcbkoy2i+eKFO0bzh8TouXLJM0=; b=V9Suos6v3yAMcYMCrlWhGv3Z5vsMQxiLkyVnoZ6OSIOvIcBlwvXKoe0GDKbrlRZt2u 5i8XWC/GShxBIyFb8J+4kClxIjEC3Ux2dP0/TM7Yn7hu7SPaT7nCWxh1UPuJAP4PTr87 gbgCZZzHCFUjwvElOA2b//BJGK+rYRTxsthiE= 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=MA5sVhd4vuss8EKHFP+StjOovdtaP1eIcRzYKvV/E2HJidNqQzqwQH56cv02XnVZ1r 7+lLemdhNBvPCpSMTFdfEs3kZrOz56IE/pZwJtjTGoml5x5vYKAfV0Y4oAo4HanlhvN8 6nIYmGIZg+mXoAqPxxeAfGznWnb6yto1DMcUU= MIME-Version: 1.0 Received: by 10.229.28.85 with HTTP; Wed, 14 Apr 2010 19:50:23 -0700 (PDT) In-Reply-To: References: <20100414.082109.29593248145846106.chat95@mac.com> <4BC5DEB4.1090208@freebsd.org> <20100415.094643.450985660335296086.chat95@mac.com> Date: Wed, 14 Apr 2010 19:50:23 -0700 Received: by 10.229.238.70 with SMTP id kr6mr1158006qcb.49.1271299823954; Wed, 14 Apr 2010 19:50:23 -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 02:50:26 -0000 On Wed, Apr 14, 2010 at 7:49 PM, Garrett Cooper wrote: > 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? Err... wait. Didn't see that the turbo boost results didn't scale linearly or align with one another until just a sec ago. Nevermind my previous comment. -Garrett