From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261175AbULMU63 (ORCPT ); Mon, 13 Dec 2004 15:58:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261173AbULMU61 (ORCPT ); Mon, 13 Dec 2004 15:58:27 -0500 Received: from e31.co.us.ibm.com ([32.97.110.129]:46491 "EHLO e31.co.us.ibm.com") by vger.kernel.org with ESMTP id S261175AbULMU4E (ORCPT ); Mon, 13 Dec 2004 15:56:04 -0500 Subject: Re: dynamic-hz From: john stultz To: Andrea Arcangeli Cc: lkml In-Reply-To: <20041211142317.GF16322@dualathlon.random> References: <20041211142317.GF16322@dualathlon.random> Content-Type: text/plain Message-Id: <1102971389.1281.427.camel@cog.beaverton.ibm.com> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.5 (1.4.5-7) Date: Mon, 13 Dec 2004 12:56:29 -0800 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2004-12-11 at 06:23, Andrea Arcangeli wrote: > This patch is quite intrusive since many HZ visible to userspace have to > be converted to USER_HZ, and most important because HZ isn't available > at compile time anymore and every variable in function of HZ must be > either changed to be in function of USER_HZ or it must be initialized at > runtime. The code has debugging code (optional at compile time) so that > I can guarantee that there cannot be any regression. Interesting patch, I know some folks have been asking about HZ=10k recently, so this could help. The only bit that worries me a bit is the change from HZ->USER_HZ for internal calculations. In my mind, USER_HZ should only be used for converting internal system ticks to userspace-visible ticks. Changing drivers to think about things in user-ticks confuses things a bit since suddenly some kernel code is thinking in user-ticks and others in system-ticks. It just muddles things a bit. thanks -john