From owner-freebsd-smp@FreeBSD.ORG Sat Dec 31 14:30:44 2005 Return-Path: X-Original-To: freebsd-smp@freebsd.org Delivered-To: freebsd-smp@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 6F18916A420 for ; Sat, 31 Dec 2005 14:30:44 +0000 (GMT) (envelope-from n.j.bouman@student.utwente.nl) Received: from netlx050.vf.utwente.nl (netlx050.vf.utwente.nl [192.87.17.19]) by mx1.FreeBSD.org (Postfix) with ESMTP id D184343D4C for ; Sat, 31 Dec 2005 14:30:39 +0000 (GMT) (envelope-from n.j.bouman@student.utwente.nl) Received: from [130.89.195.46] (snepfeu.kabel.utwente.nl [130.89.195.46]) by netlx050.vf.utwente.nl (8.11.7/HKD) with ESMTP id jBVEUXPx017271 for ; Sat, 31 Dec 2005 15:30:34 +0100 Message-ID: <43B69605.3030505@student.utwente.nl> Date: Sat, 31 Dec 2005 15:30:29 +0100 From: Niek Bouman User-Agent: Mozilla Thunderbird 1.0.6 (Windows/20050716) X-Accept-Language: en-us, en MIME-Version: 1.0 To: freebsd-smp@freebsd.org Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-UTwente-MailScanner-Information: Scanned by MailScanner. Contact helpdesk@ITBE.utwente.nl for more information. X-UTwente-MailScanner: Found to be clean X-MailScanner-From: n.j.bouman@student.utwente.nl Subject: FreeBSD 6-STABLE and HyperThreading X-BeenThere: freebsd-smp@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: FreeBSD SMP implementation group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 31 Dec 2005 14:30:44 -0000 Hi, I have a pc with a pentium4 cpu with HT support running FreeBSD 6-STABLE. In the GENERIC kernel, SMP is turned off by default. I am wondering whether it is useful to enable HT-support. In the usenet discussions, I have seen a lot about the HT security flaw that was detected a while ago. Also I read about some rumours saying that the system performance decreases with HT enabled in freebsd, because freebsd thinks that there are 2 physical cpu's and adapts the workload over them in a way that is not suitable for just one physical HT processor. Could someone give advice on whether it's wise to enable HT-support in 6-STABLE? And, is the following correct: enabling SMP (=HT in this case?) is nothing more than adding "options SMP" to the kernel config file and then do a kernel rebuild & reinstall ? And what about the scheduler? Is the usage of ULE recommended, or should i stick the old one? (I can't find that much in the handbook about HT/SMP) thanks in advance for your time and help, Niek