Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754208Ab0DTJ0n (ORCPT ); Tue, 20 Apr 2010 05:26:43 -0400 Received: from cantor2.suse.de ([195.135.220.15]:55435 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753822Ab0DTJ0m (ORCPT ); Tue, 20 Apr 2010 05:26:42 -0400 From: Thomas Renninger Organization: SUSE Products GmbH To: Arjan van de Ven Subject: Re: [PATCH 7/7] ondemand: Solve the big performance issue with ondemand during disk IO Date: Tue, 20 Apr 2010 11:29:02 +0200 User-Agent: KMail/1.12.4 (Linux/2.6.31.12-0.1-desktop; KDE/4.3.5; x86_64; ; ) Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mingo@elte.hu, peterz@infradead.org, tglx@linutronix.de, davej@redhat.com, cpufreq@vger.kernel.org References: <20100418115949.7b743898@infradead.org> <20100418120346.1b478410@infradead.org> In-Reply-To: <20100418120346.1b478410@infradead.org> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201004201129.02370.trenn@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1300 Lines: 29 On Sunday 18 April 2010 21:03:46 Arjan van de Ven wrote: > From 27966bedabea83c4f3ae77507eceb746b1f6ebae Mon Sep 17 00:00:00 2001 > From: Arjan van de Ven > Date: Sun, 18 Apr 2010 11:15:56 -0700 > Subject: [PATCH 7/7] ondemand: Solve the big performance issue with ondemand during disk IO > This algorithm falls flat on its face in the light of workloads where > you're alternatingly disk and CPU bound, such as the ever popular > "git grep", but also things like startup of programs and maildir using > email clients... much to the chagarin of Andrew Morton. Have you looked at: /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_transition_latency and /sys/devices/system/cpu/cpu0/cpufreq/ondemand/sampling_rate Transition latency comes from ACPI tables and sampling rate depends on it. Reducing the sampling rate, significantly reduces performance loss. There were bugs in this area, on latest kernels with latest (MSR switching) HW you should see: cat /sys/devices/system/cpu/cpu0/cpufreq/ondemand/sampling_rate 10000 Thomas -- 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/