Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755554AbYKJSdR (ORCPT ); Mon, 10 Nov 2008 13:33:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754658AbYKJSdB (ORCPT ); Mon, 10 Nov 2008 13:33:01 -0500 Received: from E23SMTP02.au.ibm.com ([202.81.18.163]:49544 "EHLO e23smtp02.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754528AbYKJSdA (ORCPT ); Mon, 10 Nov 2008 13:33:00 -0500 From: Vaidyanathan Srinivasan Subject: [RFC PATCH v3 0/5] Tunable sched_mc_power_savings=n To: Linux Kernel , Suresh B Siddha , Venkatesh Pallipadi , Peter Zijlstra Cc: Ingo Molnar , Dipankar Sarma , Balbir Singh , Vatsa , Gautham R Shenoy , Andi Kleen , David Collier-Brown , Tim Connors , Max Krasnyansky , Vaidyanathan Srinivasan Date: Tue, 11 Nov 2008 00:02:54 +0530 Message-ID: <20081110181526.562.69941.stgit@drishya.in.ibm.com> User-Agent: StGIT/0.14.2 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3899 Lines: 103 Hi, The existing power saving loadbalancer CONFIG_SCHED_MC attempts to run the workload in the system on minimum number of CPU packages and tries to keep rest of the CPU packages idle for longer duration. Thus consolidating workloads to fewer packages help other packages to be in idle state and save power. The current implementation is very conservative and does not work effectively across different workloads. Initial idea of tunable sched_mc_power_savings=n was proposed to enable tuning of the power saving load balancer based on the system configuration, workload characteristics and end user requirements. The power savings and performance of the given workload in an under utilised system can be controlled by setting values of 0, 1 or 2 to /sys/devices/system/cpu/sched_mc_power_savings with 0 being highest performance and least power savings and level 2 indicating maximum power savings even at the cost of slight performance degradation. Please refer to the following discussions and article for details. [1]Making power policy just work http://lwn.net/Articles/287924/ [2][RFC v1] Tunable sched_mc_power_savings=n http://lwn.net/Articles/287882/ [3][RFC PATCH v2 0/7] Tunable sched_mc_power_savings=n http://lwn.net/Articles/297306/ The following series of patch demonstrates the basic framework for tunable sched_mc_power_savings. This version of the patch incorporates comments and feedback received on the previous post. Thanks to Peter Zijlstra for the review and comments. Changes from v2: ---------------- * Fixed locking order issue in active-balance-new-idle * Moved the wakeup biasing code to wake_idle() function and preserve wake_affine function. Previous version would break wake_affine in order to aggressively consolidate tasks * Removed sched_mc_preferred_wakeup_cpu global variable and moved to doms_cur/dattr_cur and added a per_cpu pointer to appropriate storage in partitioned sched domain. This changed is needed to preserve functionality in case of partitioned sched domains * Patch on 2.6.28-rc3 kernel Notes: ------ * The patch has been tested on x86 with basic cpusets and kernbench. Correct functionality in the case of partitioned sched domain need to be analysed. Results: -------- Basic functionality of the code has not changed and the power vs performance benefits for kernbench are similar to the ones posted earlier. KERNBENCH Runs: make -j4 on a x86 8 core, dual socket quad core cpu package system SchedMC Run Time Package Idle Energy Power 0 81.61s 53.07% 52.81% 1.00x J 1.00y W 1 81.52s 40.83% 65.45% 0.96x J 0.96y W 2 74.66s 22.20% 83.94% 0.90x J 0.98y W *** This is RFC code and not for inclusion *** Please feel free to test, and let me know your comments and feedback. Thanks, Vaidy Signed-off-by: Vaidyanathan Srinivasan --- Gautham R Shenoy (1): sched: Framework for sched_mc/smt_power_savings=N Vaidyanathan Srinivasan (4): sched: activate active load balancing in new idle cpus sched: bias task wakeups to preferred semi-idle packages sched: nominate preferred wakeup cpu sched: favour lower logical cpu number for sched_mc balance include/linux/sched.h | 12 +++++++ kernel/sched.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++--- kernel/sched_fair.c | 17 +++++++++ 3 files changed, 112 insertions(+), 6 deletions(-) -- -- 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/