From owner-freebsd-current@FreeBSD.ORG Tue Aug 26 11:14:59 2003 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 5C44816A4BF for ; Tue, 26 Aug 2003 11:14:59 -0700 (PDT) Received: from mail.speakeasy.net (mail15.speakeasy.net [216.254.0.215]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2538F43F85 for ; Tue, 26 Aug 2003 11:14:58 -0700 (PDT) (envelope-from jhb@FreeBSD.org) Received: (qmail 6778 invoked from network); 26 Aug 2003 18:14:41 -0000 Received: from unknown (HELO server.baldwin.cx) ([216.27.160.63]) (envelope-sender )encrypted SMTP for ; 26 Aug 2003 18:14:41 -0000 Received: from laptop.baldwin.cx (gw1.twc.weather.com [216.133.140.1]) by server.baldwin.cx (8.12.9/8.12.9) with ESMTP id h7QIEV9s024882; Tue, 26 Aug 2003 14:14:35 -0400 (EDT) (envelope-from jhb@FreeBSD.org) Message-ID: X-Mailer: XFMail 1.5.4 on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: <20030826.233001.730554593.ken@tydfam.jp> Date: Tue, 26 Aug 2003 14:14:57 -0400 (EDT) From: John Baldwin To: Yamada Ken Takeshi cc: current@freebsd.org Subject: Re: HTT on current X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 26 Aug 2003 18:14:59 -0000 On 26-Aug-2003 Yamada Ken Takeshi wrote: > JYI, > I tested machdep.hlt_logical_cpus=0/1, buildworld, > and found no particular reason to disable HTT > as below with Zeon 2.8Ghz x 2, 1GBmem, Slow IDE HDD. > > It may not be the common case, so just for your info. > ># sysctl machdep.hlt_logical_cpus=0 ># /usr/bin/time make -j32 buildworld > 1910.29 real 2520.53 user 777.30 sys > ># sysctl machdep.hlt_logical_cpus=1 ># /usr/bin/time make -j32 buildworld > 2289.33 real 2666.66 user 645.88 sys One test is not sufficient. -current is also not the best place to test. :) When I first implemented HTT in -current and -stable, I did some worldstone benchmarks on -stable on a machine with a single HTT CPU. Note that I was comparing a UP kernel with an SMP kernel as well, so some of the speed decrease of the SMP kernel could be due to it being an SMP kernel, not due to HTT. I did 16 trials (first one was throwaway) of back-to-back buildworlds of the same version of -stable using make, make -j2, and make -j4 for the following configurations: UP, HTT, HTT with smp_idle_hlt, and HTT with pause instructions added to stable and smp_idle_hlt. The fastest build time belonged to UP without any -j option. However, the next fastest ended up being the HTT with pause and smp_idle_hlt. The averages were 19:03 and 19:42 respectively with a standard deviation in both cases of around 3.5 seconds. That is only with 15 real trials though, so I'm not sure what kind of 90% confidence interval you would get from that. I did find that with the hlt and pause additions, the HTT kernel did complete the -j2 and -j4 builds faster than the UP kernel, but those builds still took longer than a build without -j. I can't remember if I committed the addition of the pause instructions to stable or not. If I didn't then I really should do that prior to 4.9. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/