From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753864Ab0EaVhp (ORCPT ); Mon, 31 May 2010 17:37:45 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:35654 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751028Ab0EaVho convert rfc822-to-8bit (ORCPT ); Mon, 31 May 2010 17:37:44 -0400 From: "Rafael J. Wysocki" To: Arve =?iso-8859-1?q?Hj=F8nnev=E5g?= Subject: Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8) Date: Mon, 31 May 2010 23:38:55 +0200 User-Agent: KMail/1.12.4 (Linux/2.6.35-rc1-rjw; KDE/4.3.5; x86_64; ; ) Cc: Alan Stern , Florian Mickler , Peter Zijlstra , Linux PM , Brian Swetland , Alan Cox , Matthew Garrett , Thomas Gleixner , LKML , Ingo Molnar , markgross@thegnar.org References: In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Message-Id: <201005312338.55109.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday 31 May 2010, Arve Hjønnevåg wrote: > 2010/5/29 Alan Stern : > > On Sat, 29 May 2010, Arve Hjønnevåg wrote: > > > >> > In place of in-kernel suspend blockers, there will be a new type of QoS > >> > constraint -- call it QOS_EVENTUALLY. It's a very weak constraint, > >> > compatible with all cpuidle modes in which runnable threads are allowed > >> > to run (which is all of them), but not compatible with suspend. > >> > > >> This sound just like another API rename. It will work, but given that > >> suspend blockers was the name least objectionable last time around, > >> I'm not sure what this would solve. > > > > It's not just a rename. By changing this into a QoS constraint, we > > make it more generally useful. Instead of standing on its own, it > > becomes part of the PM-QOS framework. > > > > We cannot use the existing pm-qos framework. It is not safe to call > from atomic context. We've just merged a patch that fixed that if I'm not mistaken. Mark, did your PM QoS update fix that? > Also, it does not have any state constraints, so it iterates over every > registered constraint each time one of them changes. That's fixable IMO. > Nor does is currently provide any stats for debugging. That's why Alan is proposing to add that. > The original wakelock patchset supported a wakelock type so it could > be used to block more then suspend, but I had to remove this because > it "overlapped" with pm-qos. So, yes I do consider this just another > rename. It's an extension of an existing framework rather than an addition of a new one, with entirely new API and so on. Extending existing APIs is much preferred to adding new ones, in general. Rafael