From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262222AbULMLJr (ORCPT ); Mon, 13 Dec 2004 06:09:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262226AbULMLJr (ORCPT ); Mon, 13 Dec 2004 06:09:47 -0500 Received: from mail-relay-2.tiscali.it ([213.205.33.42]:60124 "EHLO mail-relay-2.tiscali.it") by vger.kernel.org with ESMTP id S262222AbULMLJk (ORCPT ); Mon, 13 Dec 2004 06:09:40 -0500 Date: Mon, 13 Dec 2004 12:08:52 +0100 From: Andrea Arcangeli To: Pavel Machek Cc: Con Kolivas , linux-kernel@vger.kernel.org Subject: Re: dynamic-hz Message-ID: <20041213110852.GQ16322@dualathlon.random> References: <20041211142317.GF16322@dualathlon.random> <20041212163547.GB6286@elf.ucw.cz> <20041212222312.GN16322@dualathlon.random> <41BCD5F3.80401@kolivas.org> <20041212234256.GK6272@elf.ucw.cz> <20041213104321.GB7340@elf.ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041213104321.GB7340@elf.ucw.cz> 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 11:43:21AM +0100, Pavel Machek wrote: > Doing lot less per timer tick is not going to help much... You cpu I also doubt we can do significantly less per timer tick. There's some new code and lock like the monotonic_lock but that's going to be lost in the noise, the irq highlevel interface has some overhead too, but that's going to be lost in the noise too. The rest pretty much cannot be avoided. I didn't measure it but I suspect the slowest part might actually be the outb_p/inb_p and the enter/exit kernel.