From owner-freebsd-amd64@FreeBSD.ORG Fri Mar 12 12:33:29 2004 Return-Path: Delivered-To: freebsd-amd64@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 434D216A4CE for ; Fri, 12 Mar 2004 12:33:29 -0800 (PST) Received: from host142.ipowerweb.com (host142.ipowerweb.com [66.235.193.61]) by mx1.FreeBSD.org (Postfix) with SMTP id 2E14143D2D for ; Fri, 12 Mar 2004 12:33:29 -0800 (PST) (envelope-from valour@thejemreport.com) Received: (qmail 83491 invoked from network); 12 Mar 2004 20:32:48 -0000 Received: from unknown (HELO thejemreport.com) (66.67.130.234) by host142.ipowerweb.com with SMTP; 12 Mar 2004 20:32:48 -0000 Message-ID: <40521E90.8090102@thejemreport.com> Date: Fri, 12 Mar 2004 15:33:20 -0500 From: Jem Matzan User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.6) Gecko/20040219 X-Accept-Language: en-us, en MIME-Version: 1.0 To: freebsd-amd64@freebsd.org References: <200403121301.i2CD1oQC076505@lurza.secnetix.de> <4051B7D3.8020404@thejemreport.com> <20040312174736.GD7661@Odin.AC.HMC.Edu> <4052130E.9060601@thejemreport.com> <20040312195958.GA32345@Odin.AC.HMC.Edu> In-Reply-To: <20040312195958.GA32345@Odin.AC.HMC.Edu> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: Peer review of AMD64/FreeBSD article X-BeenThere: freebsd-amd64@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Porting FreeBSD to the AMD64 platform List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 12 Mar 2004 20:33:29 -0000 Brooks Davis wrote: >On Fri, Mar 12, 2004 at 02:44:14PM -0500, Jem Matzan wrote: > > >>Brooks Davis wrote: >> >> >> >>>On Fri, Mar 12, 2004 at 08:14:59AM -0500, Jem Matzan wrote: >>> >>> >>> >>> >>>>Hyper-Threading seemed to help with processes that didn't require a >>>>heavy CPU load. The OpenSSL tests show it being markedly faster in the >>>>smaller algorithms, but lagging way behind the 64-bit Athlon64 when the >>>>serious number crunching comes into play. Intel's press kit shows HT >>>>(and SSE3) giving an advantage when multitasking with four desktop >>>>programs in Windows XP. It's just too hard to show that reliably though. >>>>There's a lot of anecdotal evidence to suggest that AMD64 is faster on >>>>the desktop (in X) in 64-bit mode than the Prescott is in 32-bit, but >>>>I'm having trouble proving it. >>>> >>>> >>>> >>>> >>>I think it would be a mistake to assume the HT is what accounts for >>>the performance difference. There are so many other architectural >>>differences it's hard to see how you could isolate the effects of >>>HT. My suspicition is that better performance on small >>>algorithms is due to them being more or less memory bound (and thus >>>similar to the pure synthetic benchmarks). >>> >>> >>> >>By comparing the Pentium4 to the Athlon64 in i386 mode, you can better >>see the advantage of HT Technology. This is especially evident in the >>OpenSSL tests. >> >> > >I strongly disagree. All you can see is that they differ. The >architectural differences between P4 CPUs and current generation amd64 >CPUs are a whole lot more then HT. You've got a different memory memory >system, vastly different pipeline lengths, etc. For that matter, >on paper at least, I wouldn't expect HT to help much if any in this >situation since you're not trying to do two things at once. > >-- Brooks > > > I'm pretty sure I did mention that, but I'll go over the article to make sure it's clear that the reason why there is a performance difference could be due to a number of factors (which are listed here). -Jem