From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751614AbcGLT7s (ORCPT ); Tue, 12 Jul 2016 15:59:48 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:27971 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751000AbcGLT7r (ORCPT ); Tue, 12 Jul 2016 15:59:47 -0400 X-IBM-Helo: d03dlp02.boulder.ibm.com X-IBM-MailFrom: paulmck@linux.vnet.ibm.com Date: Tue, 12 Jul 2016 12:59:26 -0700 From: "Paul E. McKenney" To: "Dr. David Alan Gilbert" Cc: Peter Zijlstra , "H. Peter Anvin" , tglx@linutronix.de, mingo@elte.hu, ak@linux.intel.com, linux-kernel@vger.kernel.org Subject: Re: [CRM114spam]: Re: Odd performance results Reply-To: paulmck@linux.vnet.ibm.com References: <20160710042639.GA4068@linux.vnet.ibm.com> <7DF218CD-22F6-4E46-A628-2138AEA3A161@infradead.org> <20160710144327.GX4650@linux.vnet.ibm.com> <20160712145551.GU30909@twins.programming.kicks-ass.net> <20160712150529.GN7094@linux.vnet.ibm.com> <27d2c710-479d-77a9-f2c6-875e9c2bc40f@zytor.com> <20160712185120.GX30909@twins.programming.kicks-ass.net> <20160712191049.GB27918@gallifrey> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160712191049.GB27918@gallifrey> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16071219-0024-0000-0000-000014175D21 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16071219-0025-0000-0000-0000429ECE6C Message-Id: <20160712195926.GY7094@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-07-12_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1607120182 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 12, 2016 at 08:10:49PM +0100, Dr. David Alan Gilbert wrote: > * Peter Zijlstra (peterz@infradead.org) wrote: > > On Tue, Jul 12, 2016 at 10:49:58AM -0700, H. Peter Anvin wrote: > > > On 07/12/16 08:05, Paul E. McKenney wrote: > > > The CPU in question (and /proc/cpuinfo should show this) has four cores > > > with a total of eight threads. The "siblings" and "cpu cores" fields in > > > /proc/cpuinfo should show the same thing. So I am utterly confused > > > about what is unexpected here? > > > > Typically threads are enumerated differently on Intel parts. Namely: > > > > cpu_id = code_id + nr_cores * smt_id > > > > which gives, for a 4 core, 2 thread part: > > > > 0-3: core 0-3, smt0 > > 4-7: core 0-3, smt1 > > > > My Core i7-2600k for example has: > > > > $ cat /sys/devices/system/cpu/cpu*/topology/thread_siblings_list > > 0,4 > > 1,5 > > 2,6 > > 3,7 > > 0,4 > > 1,5 > > 2,6 > > 3,7 > > > > The ordering Paul has, namely 0,1 for core0,smt{0,1} is not something > > I've ever seen on an Intel part. AMD otoh does enumerate their CMT stuff > > like what Paul has. > > Paul's isn't unique: > cat /sys/devices/system/cpu/cpu*/topology/thread_siblings_list > 0-1 > 0-1 > 2-3 > 2-3 > > i7-3520M CPU @ 2.90GHz (Dual core with hyperthread, Thinkpad t530, fedora 24) Glad that it is not just me! ;-) Thanx, Paul