From owner-freebsd-questions@FreeBSD.ORG Sat Dec 20 20:53:10 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id CE30D1065670 for ; Sat, 20 Dec 2008 20:53:10 +0000 (UTC) (envelope-from michael.copeland@gmail.com) Received: from mail-gx0-f19.google.com (mail-gx0-f19.google.com [209.85.217.19]) by mx1.freebsd.org (Postfix) with ESMTP id 63EB88FC08 for ; Sat, 20 Dec 2008 20:53:10 +0000 (UTC) (envelope-from michael.copeland@gmail.com) Received: by gxk12 with SMTP id 12so749849gxk.19 for ; Sat, 20 Dec 2008 12:53:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from :user-agent:mime-version:to:cc:subject:references:in-reply-to :content-type:content-transfer-encoding; bh=MyURDqcqCcgXkM29rwU9IS/5C7NlUdbXNnC/h57E7no=; b=q2xfKLR0FbCMOvf+BtDY3jFGOCCWHIfLLNlOZy1T6LSsecMyY0bfntrxXEr8HkL6vZ jrkdJ9m+gEsoI4Y56MCZir/fB5KIKFhb4SKgSqwEIPX/kzySV0XjL2YM75RKes+4groD iuiwFDh2n7i8grBVs1/cKPVXNgx1EqFUfAyfs= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=xMHL5mlkyxNt7yy57P9J5Ep7dTEbeVRk36XMCVVnYG098rBjFMVSTjaYMFfX0hXrWE oYhT4uuSnhA9FJpf15lRzVgnMLbSztvlgeuXuV/jhHb1ZgPhBbspIyVkiUlEsHlbwVBs 946mL3ewpRGxhaQwnPQWA42vPgDzJBi/3yhco= Received: by 10.150.96.10 with SMTP id t10mr8350459ybb.115.1229806389744; Sat, 20 Dec 2008 12:53:09 -0800 (PST) Received: from ?70.10.106.249? ([70.10.106.249]) by mx.google.com with ESMTPS id t26sm6520035ele.17.2008.12.20.12.53.08 (version=TLSv1/SSLv3 cipher=RC4-MD5); Sat, 20 Dec 2008 12:53:09 -0800 (PST) Message-ID: <494D5B32.50806@gmail.com> Date: Sat, 20 Dec 2008 15:53:06 -0500 From: michael User-Agent: Thunderbird 2.0.0.18 (X11/20081125) MIME-Version: 1.0 To: Brett Glass References: <200812202039.NAA10290@lariat.net> In-Reply-To: <200812202039.NAA10290@lariat.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-questions@freebsd.org Subject: Re: Status of hyperthreading in FreeBSD X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 20 Dec 2008 20:53:10 -0000 Brett Glass wrote: > "Netbooks" based on Intel's "Atom" microprocessor are turning into big > hits this Christmas season. The Atom, a super-low-power x86 processor, > is an "in-order" machine, which means that except for a few special > cases it can spend a lot of time waiting for data to arrive when it > encounters a cache miss. So, hyperthreading may make sense on this > kind of processor as compared to one with out-of-order execution. > > Which raises a question: What's the status of FreeBSD's support for > hyperthreading? As far as I know, after it was revealed that some > processes on a machine with hyperthreading could "spy" on others, and > also that hyperthreading didn't always improve performance on high end > processors, the feature was turned off by default. But on single-user > machines, or on servers where the CPU was likely to be shared by two > processes that were both privileged anyway, it might make sense to > re-enable it. But has this feature of the scheduler been maintained > well enough for this to be a good idea? If not, would it worth looking > into updating it so that FreeBSD runs well on the Atom? > > --Brett Glass > as far as i know, just enabling smp will allow ht to function. also, i don't know if intel changed ht in the new atom processor, they could have. > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to > "freebsd-questions-unsubscribe@freebsd.org"