From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262173AbULLXnj (ORCPT ); Sun, 12 Dec 2004 18:43:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262174AbULLXni (ORCPT ); Sun, 12 Dec 2004 18:43:38 -0500 Received: from mail-relay-1.tiscali.it ([213.205.33.41]:31182 "EHLO mail-relay-1.tiscali.it") by vger.kernel.org with ESMTP id S262173AbULLXnh (ORCPT ); Sun, 12 Dec 2004 18:43:37 -0500 Date: Mon, 13 Dec 2004 00:43:31 +0100 From: Andrea Arcangeli To: Con Kolivas Cc: Pavel Machek , linux-kernel@vger.kernel.org Subject: Re: dynamic-hz Message-ID: <20041212234331.GO16322@dualathlon.random> References: <20041211142317.GF16322@dualathlon.random> <20041212163547.GB6286@elf.ucw.cz> <20041212222312.GN16322@dualathlon.random> <41BCD5F3.80401@kolivas.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <41BCD5F3.80401@kolivas.org> X-GPG-Key: 1024D/68B9CB43 13D9 8355 295F 4823 7C49 C012 DFA1 686E 68B9 CB43 X-PGP-Key: 1024R/CB4660B9 CC A0 71 81 F4 A0 63 AC C0 4B 81 1D 8C 15 C8 E5 User-Agent: Mutt/1.5.6i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 13, 2004 at 10:36:19AM +1100, Con Kolivas wrote: > 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. My last number I've here is 1% for kernel compile. We're not talking fancy desktop stuff here, we're talking about raw computing servers that runs in userspace 99.9% of the time where the 1% loss is going to be multiplied dozen or hundred of times. For those HZ=1000 is a pure tangible disavantage. For desktops 1% of cpu being lost is not an issue of course.