From mboxrd@z Thu Jan 1 00:00:00 1970 From: Amir Vadai Subject: Extend irq_set_affinity_notifier() to use a call chain Date: Sun, 25 May 2014 15:15:24 +0300 Message-ID: <5381DEDC.8050204@gmail.com> Reply-To: amirv@mellanox.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" , linux-kernel , Or Gerlitz , idos@mellanox.com, Yevgeny Petrilin To: Thomas Gleixner , Ben Hutchings , "David S. Miller" Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hi, I'm working for Mellanox on mlx4_en NIC driver. We need to be able to be notified on irq affinity changes. This is because, during non-stop full bandwidth traffic, napi will poll constantly and no interrupt will be fired. Because of that, even if the user changes the irq affinity, polling will continue to be done on the original CPU that was chosen on the first packet. We would like to be notified when the affinity is changed. When such an event happen, the driver will arm the interrupts and end the napi session. An interrupt will start a new napi session on the right CPU. In order to do that, I need to add a new irq affinity notification callback (In addition to the existing cpu_rmap notification). For that I would like to extend irq_set_affinity_notifier() to have a notifier call-chain instead of a single notifier callback. I wanted to hear your opinion on this, and unless there is a better solution, will send an RFC later on. References: - http://patchwork.ozlabs.org/patch/65244/ - Review done by Thomas Glexiber to Ben Hutchings first version of the irq affinity notifiers. - http://patchwork.ozlabs.org/patch/79593/ - Final version of irq_set_affinity_notifier() that was applied Thanks, Amir