From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752099Ab1ADTCI (ORCPT ); Tue, 4 Jan 2011 14:02:08 -0500 Received: from terminus.zytor.com ([198.137.202.10]:59672 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751474Ab1ADTCH (ORCPT ); Tue, 4 Jan 2011 14:02:07 -0500 Message-ID: <4D236E47.5080500@zytor.com> Date: Tue, 04 Jan 2011 11:00:23 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101209 Fedora/3.1.7-0.35.b3pre.fc13 Thunderbird/3.1.7 MIME-Version: 1.0 To: Peter Zijlstra CC: Stephane Eranian , Lin Ming , Ingo Molnar , Andi Kleen , lkml Subject: Re: [PATCH 4/7] perf: Check if HT is supported and enabled References: <1293464211.2695.104.camel@localhost> <1293526288.2457.4.camel@minggr.sh.intel.com> <1294052312.2016.50.camel@laptop> <4D222926.9010206@zytor.com> <1294139419.2016.115.camel@laptop> <1294148675.2016.139.camel@laptop> <1294149501.2016.141.camel@laptop> In-Reply-To: <1294149501.2016.141.camel@laptop> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/04/2011 05:58 AM, Peter Zijlstra wrote: > On Tue, 2011-01-04 at 14:52 +0100, Stephane Eranian wrote: >> >> Couldn't you simply over-provision, and then when the CPU is online, use my >> ht_enabled statement to figure out whether or not you need to handle the sharing >> issue? > > That's pretty much what Lin's latest does: > > X86_FEATURE_HT && smp_num_siblings > 1 > > shows the CPU is capable of HT and will allocate the needed resources. > >>From the sound of it, it doesn't seem like it's worth optimizing out the fairly small memory allocation. -hpa