From owner-freebsd-stable Fri Jun 28 18:26:53 2002 Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8B99A37B413; Fri, 28 Jun 2002 18:26:42 -0700 (PDT) Received: from overcee.wemm.org (12-232-114-102.client.attbi.com [12.232.114.102]) by mx1.FreeBSD.org (Postfix) with ESMTP id CB61A43E06; Fri, 28 Jun 2002 18:26:41 -0700 (PDT) (envelope-from peter@wemm.org) Received: from wemm.org (localhost [127.0.0.1]) by overcee.wemm.org (Postfix) with ESMTP id 422763917; Fri, 28 Jun 2002 18:26:47 -0700 (PDT) (envelope-from peter@wemm.org) X-Mailer: exmh version 2.5 07/13/2001 with nmh-1.0.4 To: Aaron Seelye Cc: John David Duncan , freebsd-smp@FreeBSD.ORG, freebsd-stable@FreeBSD.ORG Subject: Re: 2 xeons = 4 CPUs? In-Reply-To: <200206281803.45317.aseelye@urx.com> Date: Fri, 28 Jun 2002 18:26:47 -0700 From: Peter Wemm Message-Id: <20020629012647.422763917@overcee.wemm.org> Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Aaron Seelye wrote: > Yes, that's hyperthreading (as two others before me have said), but one thing > to keep in mind is that you may want to disable it, as on some benchmarks it > actually /slows down/ the system. YMMV. The problem is that our naive scheduler assumes that all the cpu cores are equal, and would easily schedule two tasks on the same chip while leaving the other chip idle. > Aaron > > On Friday 28 June 2002 02:52 pm, John David Duncan wrote: > > Hey, > > > > I just installed 4.6-RELEASE on a dual 1.8Mhz Xeon + Tyan S2720 > > motherboard (a Relion 140 server from Penguin Computing, actually). > > When I reboot with an SMP kernel, I see: > > > > CPU: Pentium 4 (2199.76-Mhz 686-class CPU) > > CPU: Pentium 4 (2199.76-Mhz 686-class CPU) > > CPU: Pentium 4 (2199.76-Mhz 686-class CPU) > > CPU: Pentium 4 (2199.76-Mhz 686-class CPU) > > SMP: AP CPU #1 Launched! > > SMP: AP CPU #2 Launched! > > SMP: AP CPU #3 Launched! > > > > That's twice as many CPUs as I think I have, each going 400Mhz faster. Is > > this safe? Correct? Is it that hyperthreading stuff? Should I disable > > it? > > > > Thanks > > > > - JD > > > > > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > > with "unsubscribe freebsd-stable" in the body of the message > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-smp" in the body of the message > Cheers, -Peter -- Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com "All of this is for nothing if we don't go to the stars" - JMS/B5 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message