Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965084AbVJ1EAq (ORCPT ); Fri, 28 Oct 2005 00:00:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965085AbVJ1EAq (ORCPT ); Fri, 28 Oct 2005 00:00:46 -0400 Received: from xproxy.gmail.com ([66.249.82.194]:8379 "EHLO xproxy.gmail.com") by vger.kernel.org with ESMTP id S965084AbVJ1EAq convert rfc822-to-8bit (ORCPT ); Fri, 28 Oct 2005 00:00:46 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=emslsCWpw+kQldWRiedFim/13kvrYUp/o0ryZbRu4/EYFU7aFqhXjEKDTb3dZ6AgpykdWkxBfG0iokIzFB1YWICODgwyDP1sibZuOe1lEi07N3N/7dX/NK99kmF1uG4E6ue3q5xbWQD7E/HCsqnoKEfUhgvnrLV8NVr8O1zUf2Q= Message-ID: <9a8748490510272100u453e73e3mc957a673eeb8498e@mail.gmail.com> Date: Fri, 28 Oct 2005 06:00:45 +0200 From: Jesper Juhl To: Lee Revell Subject: Re: The "best" value of HZ Cc: Alistair John Strachan , Claudio Scordino , linux-kernel@vger.kernel.org, kernelnewbies@nl.linux.org In-Reply-To: <1130471136.4363.29.camel@mindpipe> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Content-Disposition: inline References: <200510280118.42731.cloud.of.andor@gmail.com> <200510280331.21112.s0348365@sms.ed.ac.uk> <1130471136.4363.29.camel@mindpipe> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2007 Lines: 44 On 10/28/05, Lee Revell wrote: > On Fri, 2005-10-28 at 03:31 +0100, Alistair John Strachan wrote: > > On Friday 28 October 2005 00:18, Claudio Scordino wrote: > > > Hi, > > > > > > during the last years there has been a lot of discussion about the > > > "best" value of HZ... On i386 was 100, then became 1000, and finally was > > > set to 250. I'm thinking to do an evaluation of this parameter using > > > different architectures. > > > > > > Has anybody thought to give the possibility to modify the value of HZ at > > > boot time instead of at compile time ? This would allow to easily test > > > different values on different machines and create a table containing the > > > "best" value for each architecture... At this moment, instead, we have to > > > recompile the kernel for each different value :( > > > > > > Do you think there would be much work to do that ? > > > Do you think it would be a desired feature the knowledge of the best value > > > for each architecture with more precision ? > > > > Google for "dynticks". There's obviously an overhead associated with HZ not > > being a constant (the compiler cannot optimise many expressions), but the > > feature is being worked on nonetheless. > > > > Well Linus had the best idea in that thread (as usual) which was to > implement "dynamic ticks" by leaving HZ a constant, setting it to a high > value, and skipping ticks when idle. Has there been any work in that > direction? > i did a bit of work in that area, but the stuff I came up with never seemed to work right, so I dropped it. -- Jesper Juhl Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html Plain text mails only, please http://www.expita.com/nomime.html - 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/