From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756796Ab0IBUK5 (ORCPT ); Thu, 2 Sep 2010 16:10:57 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:43671 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752773Ab0IBUKz (ORCPT ); Thu, 2 Sep 2010 16:10:55 -0400 From: "Rafael J. Wysocki" To: markgross@thegnar.org Subject: Re: [PATCH] pm_qos: Add system bus performance parameter Date: Thu, 2 Sep 2010 22:09:20 +0200 User-Agent: KMail/1.13.5 (Linux/2.6.36-rc3-rjw+; KDE/4.4.4; x86_64; ; ) Cc: Kevin Hilman , Saravana Kannan , linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, James Bottomley , Frederic Weisbecker , Jonathan Corbet , Matthew Garrett References: <1282882403-29824-1-git-send-email-skannan@codeaurora.org> <87hbigqg8d.fsf@deeprootsystems.com> <20100902140546.GA2818@gvim.org> In-Reply-To: <20100902140546.GA2818@gvim.org> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201009022209.20354.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, September 02, 2010, mark gross wrote: > On Fri, Aug 27, 2010 at 07:31:46AM -0700, Kevin Hilman wrote: > > Saravana Kannan writes: > > > > > Some drivers/devices might need some minimum system bus performance to > > > provide acceptable service. Provide a PM QoS parameter to send these requests > > > to. > > > > > > The new parameter is named "system bus performance" since it is generic enough > > > for the unit of the request to be frequency, bandwidth or something else that > > > might be appropriate. It's up to each implementation of the QoS provider to > > > define what the unit of the request would be. > > > > > > Signed-off-by: Saravana Kannan > > > > With this current design, only one system-wide bus would be managed. > > What if a platform has more than one independently scalable bus? > > > > I think the only scalable way to handle this kind of thing is to have > > per-device QoS constraints that can then be combined/aggregated by parent > > devices/busses. > > > > At LPC this year, I've proposed per-device QoS constraints[1] as a topic > > for the PM mini-conf. I hope some folks from the MSM camp can be there > > for these discussions. > > > > Kevin > > > > [1] http://www.linuxplumbersconf.org/2010/ocw/proposals/819 > > I thought a pm_qos like thing per bus would be a patch or you where > going to put up to the driver model. ;) > > The current pm_qos would stick around for higher level pm_qos things. > So making the system bus and changing to a summation aggregation would > be temporary thing. > > Or are you you saying we shouldn't put system_bus into pm_qos at all and > instead we should put effort into adding it to the driver model for > buses? Hmm, well, what's system_bus? Rafael