From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262180AbULMA1u (ORCPT ); Sun, 12 Dec 2004 19:27:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262181AbULMA1u (ORCPT ); Sun, 12 Dec 2004 19:27:50 -0500 Received: from mail-relay-3.tiscali.it ([213.205.33.43]:14241 "EHLO mail-relay-3.tiscali.it") by vger.kernel.org with ESMTP id S262180AbULMA1t (ORCPT ); Sun, 12 Dec 2004 19:27:49 -0500 Date: Mon, 13 Dec 2004 01:27:51 +0100 From: Andrea Arcangeli To: Con Kolivas Cc: Pavel Machek , linux-kernel@vger.kernel.org Subject: Re: dynamic-hz Message-ID: <20041213002751.GP16322@dualathlon.random> References: <20041211142317.GF16322@dualathlon.random> <20041212163547.GB6286@elf.ucw.cz> <20041212222312.GN16322@dualathlon.random> <41BCD5F3.80401@kolivas.org> <20041212234331.GO16322@dualathlon.random> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 11:18:15AM +1100, Con Kolivas wrote: > Thanks. I have to admit that the real reason I wrote this email was for > this discussion to go on record so that desktop users would not get > inappropriately excited by this change. Sure, desktop doesn't need this, the reason somebody is asking for it, is that the desktop stuff hurted some other non-desktop usages. Infact my 2.4 tree was setting by default HZ=1000 if 'desktop' paramter was passed to the kernel (so that I could lower the timeslice accordingly too, without losing the effect of the nicelevels between nice 0 and +19). The other new case where I'm asked for this feature is again not the desktop but the high end laptop with cpu throttling down to 80mhz, and what Pavel mentioned about the lower consumption. Perhaps we could do variable HZ there, though I doubt it has a pit that can be reprogrammed with sane performance. Very few people are going to get real benefit from HZ=1000, but I certainly agree it worth to keep HZ=1000 on desktops since on a idle machine the downside of the more frequent irq sure isn't measurable, while having shorter timeslices may be visible with many tasks, and shorter timeslices requires faster HZ to preserve the nicelevels.