From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751311AbcGJFRl (ORCPT ); Sun, 10 Jul 2016 01:17:41 -0400 Received: from merlin.infradead.org ([205.233.59.134]:38852 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750727AbcGJFRk (ORCPT ); Sun, 10 Jul 2016 01:17:40 -0400 User-Agent: K-9 Mail for Android In-Reply-To: <20160710042639.GA4068@linux.vnet.ibm.com> References: <20160710042639.GA4068@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Subject: Re: Odd performance results From: Peter Zijlstra Date: Sun, 10 Jul 2016 07:17:19 +0200 To: paulmck@linux.vnet.ibm.com, hpa@zytor.com, tglx@linutronix.de, mingo@elte.hu, ak@linux.intel.com CC: linux-kernel@vger.kernel.org Message-ID: <7DF218CD-22F6-4E46-A628-2138AEA3A161@infradead.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? -- Sent from my Android device with K-9 Mail. Please excuse my brevity.