From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [RFC/PATCH] PM QoS: main memory throughput constraints Date: Fri, 30 Sep 2011 22:28:07 +0200 Message-ID: <201109302228.07589.rjw@sisk.pl> References: Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from ogre.sisk.pl ([217.79.144.158]:40413 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751524Ab1I3UZw (ORCPT ); Fri, 30 Sep 2011 16:25:52 -0400 In-Reply-To: Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Jean Pihet Cc: Kevin Hilman , Paul Walmsley , Linux PM mailing list , linux-omap@vger.kernel.org, Benoit Cousson Hi, On Friday, September 30, 2011, Jean Pihet wrote: > Hi, > > Here is a patch which adds a PM_QOS_MEMORY_THROUGHPUT class to the PM > QoS framework. The idea is to provide a memory or SDMA throughput > constraints class, which can be applied to the low level platform code > using the callback notification mechanism and also a MISC /dev entry > for the constraints from user space. > > The first user of this class of constraints is the OMAP platform. The > aggregated constraint is fed to the DVFS layer in order to control the > main interconnect (L3) frequency and so the memory bandwidth. This > comes as a subsequent patch. > > This patch is RFC since more throughput constraints could be added in > the future, in order to control more clocks in the system. Is it worth > adding a class for every new subsystem to control? > > What do you think? > > The patch follows asap as a reply to this message. It applies on > Rafael' latest linux-pm tree, cf. > https://github.com/rjwysocki/linux-pm/commits/pm-qos. Quite frankly, I'm not very fond of creating more special device files for PM QoS at this point. It would be nice if you could give an example of how you intend to use it, especially from the user space's viewpoint. Thanks, Rafael