From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753052Ab0A2Q0a (ORCPT ); Fri, 29 Jan 2010 11:26:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752708Ab0A2Q02 (ORCPT ); Fri, 29 Jan 2010 11:26:28 -0500 Received: from e38.co.us.ibm.com ([32.97.110.159]:41906 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752483Ab0A2Q01 (ORCPT ); Fri, 29 Jan 2010 11:26:27 -0500 Message-ID: <4B630C27.1060405@austin.ibm.com> Date: Fri, 29 Jan 2010 10:26:15 -0600 From: Joel Schopp User-Agent: Thunderbird 2.0.0.23 (X11/20090817) MIME-Version: 1.0 To: Gabriel Paubert CC: Peter Zijlstra , ego@in.ibm.com, linux-kernel@vger.kernel.org, Ingo Molnar , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCHv3 2/2] powerpc: implement arch_scale_smt_power for Power7 References: <1264017638.5717.121.camel@jschopp-laptop> <1264017847.5717.132.camel@jschopp-laptop> <1264548495.12239.56.camel@jschopp-laptop> <1264720855.9660.22.camel@jschopp-laptop> <20100129122536.GA11156@iram.es> In-Reply-To: <20100129122536.GA11156@iram.es> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Gabriel Paubert wrote: > On Thu, Jan 28, 2010 at 05:20:55PM -0600, Joel Schopp wrote: > >> On Power7 processors running in SMT4 mode with 2, 3, or 4 idle threads >> there is performance benefit to idling the higher numbered threads in >> the core. >> >> > > Really 2, 3, or 4? When you have 4 idle threads out of 4, performance > becomes a minor concern, no? ;-) > > Gabriel > Yes, but going from 4 idle to 3 idle you want to keep the slanted weights. If you ignored 4 you'd place wrong and then correct it after the fact. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e36.co.us.ibm.com (e36.co.us.ibm.com [32.97.110.154]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e36.co.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 1F9D4B7D1F for ; Sat, 30 Jan 2010 03:26:28 +1100 (EST) Received: from d03relay03.boulder.ibm.com (d03relay03.boulder.ibm.com [9.17.195.228]) by e36.co.us.ibm.com (8.14.3/8.13.1) with ESMTP id o0TGNceG016395 for ; Fri, 29 Jan 2010 09:23:38 -0700 Received: from d03av06.boulder.ibm.com (d03av06.boulder.ibm.com [9.17.195.245]) by d03relay03.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o0TGQIn3067274 for ; Fri, 29 Jan 2010 09:26:18 -0700 Received: from d03av06.boulder.ibm.com (loopback [127.0.0.1]) by d03av06.boulder.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id o0TGSRpj005985 for ; Fri, 29 Jan 2010 09:28:28 -0700 Message-ID: <4B630C27.1060405@austin.ibm.com> Date: Fri, 29 Jan 2010 10:26:15 -0600 From: Joel Schopp MIME-Version: 1.0 To: Gabriel Paubert Subject: Re: [PATCHv3 2/2] powerpc: implement arch_scale_smt_power for Power7 References: <1264017638.5717.121.camel@jschopp-laptop> <1264017847.5717.132.camel@jschopp-laptop> <1264548495.12239.56.camel@jschopp-laptop> <1264720855.9660.22.camel@jschopp-laptop> <20100129122536.GA11156@iram.es> In-Reply-To: <20100129122536.GA11156@iram.es> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: linux-kernel@vger.kernel.org, Ingo Molnar , linuxppc-dev@lists.ozlabs.org, Peter Zijlstra , ego@in.ibm.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Gabriel Paubert wrote: > On Thu, Jan 28, 2010 at 05:20:55PM -0600, Joel Schopp wrote: > >> On Power7 processors running in SMT4 mode with 2, 3, or 4 idle threads >> there is performance benefit to idling the higher numbered threads in >> the core. >> >> > > Really 2, 3, or 4? When you have 4 idle threads out of 4, performance > becomes a minor concern, no? ;-) > > Gabriel > Yes, but going from 4 idle to 3 idle you want to keep the slanted weights. If you ignored 4 you'd place wrong and then correct it after the fact.