From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758865AbXJKPJH (ORCPT ); Thu, 11 Oct 2007 11:09:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754261AbXJKPI4 (ORCPT ); Thu, 11 Oct 2007 11:08:56 -0400 Received: from mga09.intel.com ([134.134.136.24]:32927 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752331AbXJKPIz (ORCPT ); Thu, 11 Oct 2007 11:08:55 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.21,260,1188802800"; d="scan'208";a="169892492" Date: Thu, 11 Oct 2007 08:08:04 -0700 From: Mark Gross To: Andrew Morton Cc: arjan@infradead.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, linux-pm@lists.linux-foundation.org, mark.gross@intel.com Subject: Re: pm qos infrastructure and interface Message-ID: <20071011150804.GA7293@linux.intel.com> Reply-To: mgross@linux.intel.com References: <20071004215139.GA20078@linux.intel.com> <20071010221704.6e438c71.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071010221704.6e438c71.akpm@linux-foundation.org> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 10, 2007 at 10:17:04PM -0700, Andrew Morton wrote: > On Thu, 4 Oct 2007 14:51:39 -0700 Mark Gross wrote: > > > The following patch is a generalization of the latency.c implementation > > done by Arjan last year. It provides infrastructure for more than one > > parameter, and exposes a user mode interface for processes to register > > pm_qos expectations of processes. > > > > > > This interface provides a kernel and user mode interface for registering > > performance expectations by drivers, subsystems and user space > > applications on one of the parameters. > > > > Currently we have {cpu_dma_latency, network_latency, network_throughput} > > as the initial set of pm_qos parameters. > > > > The infrastructure exposes multiple misc device nodes one per > > implemented parameter. The set of parameters implement is defined by > > pm_qos_power_init() and pm_qos_params.h. This is done because having > > the available parameters being runtime configurable or changeable from a > > driver was seen as too easy to abuse. > > I'm a bit surprised that this change appears to have no configurability. > If one has set CONFIG_PM=n (for example), shouldn't it all go away? We considered that as an option but as latency.c didn't offer it I didn't either. I could see the user mode interface portion of the implementation be made as a compile time option but the kernel infrastructure will continue to be needed by at least cpu-idel, pcm_native.c and ipw2100. You know it could make sense to have the user mode interface part of the patch as configurable or a build time dependent of sysfs and misc device support for the linux-tiny guys. Is it practical to make a linux-tiny without the sysfs infrastructure needed to make a misc device? I'll ask on the linux-tiny list. --mgross