From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lina Iyer Subject: Re: [PATCH v3 3/4] irq: Allow multiple clients to register for irq affinity notification Date: Fri, 10 Oct 2014 09:11:06 -0600 Message-ID: <20141010151106.GC2128@ilina-mac.qualcomm.com> References: <1409170479-29955-1-git-send-email-lina.iyer@linaro.org> <1409170479-29955-4-git-send-email-lina.iyer@linaro.org> <20140902184305.GB91995@ilina-mac.local> <20140925155027.GG1004@ilina-mac.local> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Return-path: Received: from mail-pd0-f170.google.com ([209.85.192.170]:62222 "EHLO mail-pd0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753555AbaJJPLK (ORCPT ); Fri, 10 Oct 2014 11:11:10 -0400 Received: by mail-pd0-f170.google.com with SMTP id p10so1834492pdj.29 for ; Fri, 10 Oct 2014 08:11:09 -0700 (PDT) Content-Disposition: inline In-Reply-To: Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Thomas Gleixner Cc: khilman@linaro.org, ulf.hansson@linaro.org, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, rjw@rjwysocki.net, daniel.lezcano@linaro.org On Wed, Oct 08 2014 at 09:03 -0600, Thomas Gleixner wrote: >On Thu, 25 Sep 2014, Lina Iyer wrote: >> > How would a general "keep track of the targets of all interrupts in >> > the system" mechanism make use of this? >> Sorry, I do not understand your question. >> PM QoS is only interested in the IRQs specified in the QoS request. If >> there are no requests that need to be associated with an IRQ, then PM >> QoS will not register for an affinity change notification. > >Right, and I really hate the whole per irq notifier. It's a rats nest >of life time issues and other problems. > >It also does not tell you whether an irq is disabled, reenabled or >removed, which will change the qos constraints as well unless you >plaster all drivers with updates to qos for those cases. > >So what about adding a qos field to irq_data itself, have a function >to update it and let the irq core keep track of the per cpu irq >relevant qos constraints and provide an evaluation function or a >notifier for the PM/idle code? If that isnt intrusive in the IRQ core, then we can make it work for PM QoS. The issue that I am concerned is that, it might result in back and forth between IRQ and PM QoS frameworks. If that doesnt happen, then we are good with this approach. > >That's going to need some serious thought as well, but it should avoid >most of the nasty notifier and lifetime issue which the per irq >notifiers provide. Sure. I will look into this. > >Thoughts? Thank you. Lina > > > >