From owner-freebsd-current@FreeBSD.ORG Wed Sep 14 20:02:47 2011 Return-Path: Delivered-To: freebsd-current@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id DDD42106564A; Wed, 14 Sep 2011 20:02:47 +0000 (UTC) (envelope-from aboyer@averesystems.com) Received: from zimbra.averesystems.com (75-149-8-245-Pennsylvania.hfc.comcastbusiness.net [75.149.8.245]) by mx1.freebsd.org (Postfix) with ESMTP id 95E408FC14; Wed, 14 Sep 2011 20:02:47 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by zimbra.averesystems.com (Postfix) with ESMTP id 89BE58BC023; Wed, 14 Sep 2011 16:05:24 -0400 (EDT) X-Virus-Scanned: amavisd-new at averesystems.com Received: from zimbra.averesystems.com ([127.0.0.1]) by localhost (zimbra.averesystems.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id i51Rnj1zR979; Wed, 14 Sep 2011 16:05:19 -0400 (EDT) Received: from [10.0.1.192] (fw.arriad.com [10.0.0.16]) by zimbra.averesystems.com (Postfix) with ESMTPSA id 6E6CD8BC003; Wed, 14 Sep 2011 16:05:19 -0400 (EDT) Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: text/plain; charset=us-ascii From: Andrew Boyer In-Reply-To: <4E7106DE.40707@FreeBSD.org> Date: Wed, 14 Sep 2011 16:02:41 -0400 Content-Transfer-Encoding: quoted-printable Message-Id: <70B018CB-4658-45DD-929E-A953B299E737@averesystems.com> References: <2C3C4570-C5F9-42F5-AA81-900151590DB8@averesystems.com> <4E7106DE.40707@FreeBSD.org> To: Andriy Gapon X-Mailer: Apple Mail (2.1084) Cc: freebsd-current@FreeBSD.org Subject: Re: Identification of HTT cores on newer (CPUID leaf 11) Intel processors X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 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: Wed, 14 Sep 2011 20:02:47 -0000 On Sep 14, 2011, at 3:56 PM, Andriy Gapon wrote: > on 14/09/2011 20:59 Andrew Boyer said the following: >> When FreeBSD examines the CPU topology using CPUID leaf 11 in >> topo_probe_0xb(), it never sets hyperthreading_cpus. At the end of >> topo_probe_0x4() it sets hyperthreading_cpus =3D cpu_logical. >>=20 >> Adding that assignment to line 316 of sys/amd64/amd64/mp_machdep.c = seems to >> do the right thing on a system with two quad-core E5620 CPUs. The = APIC IDs >> that appear when SMT is enabled in the BIOS get marked AP/HT. >>=20 >> Do you agree? >=20 > I agree, but... > But see this: > = http://thread.gmane.org/gmane.os.freebsd.devel.hackers/44007/focus=3D44024= >=20 > Someone long ago has decided that new HTT is not the same as old HTT = and that > some rules that apply to old HTT should not apply to new HTT. Even = the name. > I think that that's not correct. > But it doesn't seem that I am able to engage into a discussion the = person who > made that decision. Also I can not find any other interested = developer either. >=20 > Anyway, hyperthreading_cpus variable is useless beyond dmesg = cosmetics. > And I don't think that any of my changes affected the dmesg output. >=20 > In my "avgBSD" I have different SMP topology code, but it's not ready = yet to be > submitted for merge into the main tree. >=20 > --=20 > Andriy Gapon Actually, it's not useless. If you don't set it to something other than = zero the machdep.hyperthreading_allowed tunable doesn't do anything, = since it can't tell which CPUs are actually HTT. -Andrew -------------------------------------------------- Andrew Boyer aboyer@averesystems.com