From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262225AbULMLXQ (ORCPT ); Mon, 13 Dec 2004 06:23:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262226AbULMLXQ (ORCPT ); Mon, 13 Dec 2004 06:23:16 -0500 Received: from gprs214-177.eurotel.cz ([160.218.214.177]:51333 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S262225AbULMLWm (ORCPT ); Mon, 13 Dec 2004 06:22:42 -0500 Date: Mon, 13 Dec 2004 12:22:29 +0100 From: Pavel Machek To: Hans Kristian Rosbach Cc: Andrew Morton , Con Kolivas , andrea@suse.de, Linux Kernel Mailing List Subject: Re: dynamic-hz Message-ID: <20041213112229.GS6272@elf.ucw.cz> References: <20041211142317.GF16322@dualathlon.random> <20041212163547.GB6286@elf.ucw.cz> <20041212222312.GN16322@dualathlon.random> <41BCD5F3.80401@kolivas.org> <20041213030237.5b6f6178.akpm@osdl.org> <1102936790.17227.24.camel@linux.local> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1102936790.17227.24.camel@linux.local> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.6+20040722i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > > The performance benefit, if any, is often lost in noise during > > > benchmarks and when there, is less than 1%. So I was wondering if you > > > had some specific advantage in mind for this patch? Is there some > > > arch-specific advantage? I can certainly envision disadvantages to lower Hz. > > > > There are apparently some laptops which exhibit appreciable latency between > > the start of ACPI sleep and actually consuming less power. The 1ms wakeup > > frequency will shorten battery life on these machines significantly. (I > > forget the exact numbers - Len will know). > > Is there any recommended lower bound setting? > Would there be a point in recommending lower settings for desktops > running only text consoles opposed to X desktops? I tried defining HZ to 10 once, and there are some #if arrays in the kernel that prevented me from doing that. Some drivers do timeouts based on jiffies; having HZ=1 may turn 20msec timeout into 1sec, that could hurt a lot in the error case... Pavel -- People were complaining that M$ turns users into beta-testers... ...jr ghea gurz vagb qrirybcref, naq gurl frrz gb yvxr vg gung jnl!