Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 10 Jul 2002 17:27:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 10 Jul 2002 17:27:18 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:61703 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id ; Wed, 10 Jul 2002 17:27:17 -0400 Message-ID: <3D2CA6E3.CB5BC420@zip.com.au> Date: Wed, 10 Jul 2002 14:28:03 -0700 From: Andrew Morton X-Mailer: Mozilla 4.79 [en] (X11; U; Linux 2.4.19-pre8 i686) X-Accept-Language: en MIME-Version: 1.0 To: "Grover, Andrew" CC: Linux Subject: Re: HZ, preferably as small as possible References: <59885C5E3098D511AD690002A5072D3C02AB7F88@orsmsx111.jf.intel.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1117 Lines: 29 "Grover, Andrew" wrote: > > I'd like to see HZ closer to 100 than 1000, for CPU power reasons. Processor > power states like C3 may take 100 microseconds+ to enter/leave - time when > both the CPU isn't doing any work, but still drawing power as if it was. We > pop out of C3 whenever there is an interrupt, so reducing timer interrupts > is good from a power standpoint by amortizing the transition penalty over a > longer period of power savings. That makes a ton of sense. > But on the other hand, increasing HZ has perf/latency benefits, yes? Have > these been quantified? Not that I'm aware of. And I'd regard any such claims with some scepticism. > I'd either like to see a HZ that has balanced > power/performance, or could we perhaps detect we are on a system that cares > about power (aka a laptop) and tweak its value at runtime? It's all rather fishy. - - 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/