From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ECA15C2D0DB for ; Wed, 22 Jan 2020 12:43:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C703724684 for ; Wed, 22 Jan 2020 12:43:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729076AbgAVMnK (ORCPT ); Wed, 22 Jan 2020 07:43:10 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:37650 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726204AbgAVMnJ (ORCPT ); Wed, 22 Jan 2020 07:43:09 -0500 Received: from [5.158.153.52] (helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1iuFLM-0003OI-VI; Wed, 22 Jan 2020 13:42:49 +0100 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id 8960C101F92; Wed, 22 Jan 2020 13:42:48 +0100 (CET) From: Thomas Gleixner To: l00520965 Cc: linfeilong@huawei.com, hushiyuan@huawei.com, LiuChao , linux-kernel@vger.kernel.org, PJ Waskiewicz , Neil Horman Subject: Re: [RFC] irq: Skip printing irq when desc->action is null even if any_count is not zero In-Reply-To: <20200121130959.22589-1-liuchao173@huawei.com> References: <20200121130959.22589-1-liuchao173@huawei.com> Date: Wed, 22 Jan 2020 13:42:48 +0100 Message-ID: <87k15jek6v.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Chao, l00520965 writes: > When desc->action is empty, there is no need to print out the irq and its' > count in each cpu. The desc is not alloced in request_irq or freed in > free_irq. request/free_irq() never allocate/free irq descriptors. > So some PCI devices, such as rtl8139, uses request_irq and free_irq, All PCI devices use some variant of request_irq()/free_irq(). The interrupt descriptors are allocated by the underlying PCI machinery. They are only allocated/freed when the device driver is loaded/removed. And this property exists for _ALL_ interrupts independent of PCI. > which only modify the action of desc. So /proc/interrupts could be > like this: I think you want to explain: If an interrupt is released via free_irq() without removing the underlying irq descriptor, the interrupt count of the irq descriptor is not reset. /proc/interrupt shows such interrupts with an empty action handler name: > CPU0 CPU1 > 38: 46 0 GICv3 36 Level ehci_hcd:usb1 > 39: 66 0 GICv3 37 Level irqbalance fails to detect that this interrupt is not longer in use and parses the last word in the line 'Level' as the action handler name. > Irqbalance gets the list of interrupts according to /proc/interrupts. In > this case, irqbalance does not remove the interrupt from the balance list, > and the last string in this line,which is Level, is used as irq_name. Right, this is historic behaviour and I don't know how irqbalance dealt with that in the past 20+ years. At least I haven't seen any complaints. I'm not opposed to suppress the output, but I really want the opinion of the irqbalance maintainers on that. > Or we can clear desc->kstat_irqs in each cpu in free_irq when > desc->action is null? No, we can't. The historic behaviour is that the total interrupt count for a device is maintained independent of the number of request/free_irq() pairs. > Signed-off-by: LiuChao > Reviewed-by: Thomas Gleixner I really can't remember that I have reviewed this patch already. Please don't add tags which claim that some one has reviewed or acked your patch unless you really got that Reviewed-by or Acked-by from that person. Thanks, tglx