From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933373AbcGLPFX (ORCPT ); Tue, 12 Jul 2016 11:05:23 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:23331 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753982AbcGLPFW (ORCPT ); Tue, 12 Jul 2016 11:05:22 -0400 X-IBM-Helo: d03dlp02.boulder.ibm.com X-IBM-MailFrom: paulmck@linux.vnet.ibm.com Date: Tue, 12 Jul 2016 08:05:29 -0700 From: "Paul E. McKenney" To: Peter Zijlstra Cc: hpa@zytor.com, tglx@linutronix.de, mingo@elte.hu, ak@linux.intel.com, linux-kernel@vger.kernel.org Subject: 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160712145551.GU30909@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16071215-0008-0000-0000-000005094C04 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16071215-0009-0000-0000-0000393D6F9D Message-Id: <20160712150529.GN7094@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-07-12_07:,, 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-1607120137 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 12, 2016 at 04:55:51PM +0200, Peter Zijlstra wrote: > On Sun, Jul 10, 2016 at 07:43:27AM -0700, Paul E. McKenney wrote: > > On Sun, Jul 10, 2016 at 07:17:19AM +0200, Peter Zijlstra wrote: > > > > > > > > > On 10 July 2016 06:26:39 CEST, "Paul E. McKenney" wrote: > > > >Hello! > > > > > > > >So I ran a quick benchmark which showed stair-step results. I > > > >immediately > > > >thought "Ah, this is due to CPU 0 and 1, 2 and 3, 4 and 5, and 6 and 7 > > > >being threads in a core." Then I thought "Wait, this is an x86!" > > > >Then I dumped out cpu*/topology/thread_siblings_list, getting the > > > >following: > > > > > > > > cpu0/topology/thread_siblings_list: 0-1 > > > > cpu1/topology/thread_siblings_list: 0-1 > > > > cpu2/topology/thread_siblings_list: 2-3 > > > > cpu3/topology/thread_siblings_list: 2-3 > > > > cpu4/topology/thread_siblings_list: 4-5 > > > > cpu5/topology/thread_siblings_list: 4-5 > > > > cpu6/topology/thread_siblings_list: 6-7 > > > > cpu7/topology/thread_siblings_list: 6-7 > > > > > > > > > I'm guessing this is an AMD bulldozer like machine? > > > > /proc/cpuinfo thinks otherwise: > > > > processor : 0 > > vendor_id : GenuineIntel > > cpu family : 6 > > model : 60 > > model name : Intel(R) Core(TM) i7-4710MQ CPU @ 2.50GHz > > Weird, I've never seen an Intel box do that before... hpa, any idea? or > is this just one weird BIOS. ;-) It is a Lenovo W541 laptop, for whatever that might be worth. Roughly on year old. Thanx, Paul