Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755281AbaJHPDf (ORCPT ); Wed, 8 Oct 2014 11:03:35 -0400 Received: from www.linutronix.de ([62.245.132.108]:38294 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751280AbaJHPDe (ORCPT ); Wed, 8 Oct 2014 11:03:34 -0400 Date: Wed, 8 Oct 2014 17:03:29 +0200 (CEST) From: Thomas Gleixner To: Lina Iyer 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 Subject: Re: [PATCH v3 3/4] irq: Allow multiple clients to register for irq affinity notification In-Reply-To: <20140925155027.GG1004@ilina-mac.local> Message-ID: 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> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? 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. Thoughts? tglx -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/