Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751572Ab0AZKCO (ORCPT ); Tue, 26 Jan 2010 05:02:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751860Ab0AZKCK (ORCPT ); Tue, 26 Jan 2010 05:02:10 -0500 Received: from lucidpixels.com ([75.144.35.66]:46216 "EHLO lucidpixels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751043Ab0AZKCK (ORCPT ); Tue, 26 Jan 2010 05:02:10 -0500 Date: Tue, 26 Jan 2010 05:02:08 -0500 (EST) From: Justin Piszcz To: linux-kernel@vger.kernel.org Subject: Hyperthreading on Core i7s: To use or not to use? Message-ID: User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1348 Lines: 36 Hello, Should the 'correct' kernel [CPU] configuration for a core i7 860/870..? - Multi-core support - Cores: 8 - SMT: Enabled/ON >From CONFIG_SCHED_SMT: . SMT scheduler support improves the CPU scheduler's decision making . . when dealing with Intel Pentium 4 chips with HyperThreading at a . . cost of slightly increased overhead in some places. If unsure say . . N here. . Does this also 'help' and/or 'apply' as much when dealing with Core i7s? -- Quick little benchmark (pbzip2 -9 linux kernel source), the benchmark is really within the noise (8 on/off) - Multicore(8)/HT(Off) = 73.72user 0.33system 0:09.50elapsed 779%CPU (0avgtext+0avgdata 458528maxresident - Multicore(8)/HT(On) = 74.28user 0.40system 0:09.67elapsed 772%CPU (0avgtext+0avgdata 428304maxresident - Multicore(4)/HT(On) = 68.76user 0.30system 0:17.44elapsed 396%CPU (0avgtext+0avgdata 213616maxresident)k -- Has anyone done any in-depth benchmarking for the core i7s that have multiple cores and HT disabled/enabled? Justin. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/