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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CF65EC3DA4A for ; Fri, 2 Aug 2024 01:45:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:References:CC:To:From:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=SG6wsk1H49LN1Elf+KCoShYjLO38+rhhHsv3zebml7A=; b=YjB43Y/TBMgi1WxG/+CNnCGo8T oZITtiU4o7+lyCdK0AKWXB7BFd+iLUxOukTifElzvKVd0am6s7zfYz3GOrK5+30tQGtZtVo3FBMu7 1rHnRZXoHfROQSDnM9o5wQ6ieHC2EazamkkBTrOwIXIgM9lGFEhlf36sNdNfrLIi1Sxp7uij8NCJd 1Hmpn4bg/Q9CzGLAkwNfar4AzBejAZi8FzHB6tmmdaj9wz6QbN4Yi4vhy5/L+EHynGtZp3prtACcT WxU0gwo7503A3OBLy/0T/nOq4yLBFTdh3q/IuTcf45w/7l0uo/jPDGl04h563R/NP9z8vMhd73XP5 Eynb+9IQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sZhLd-00000007JPp-1ppG; Fri, 02 Aug 2024 01:44:49 +0000 Received: from szxga03-in.huawei.com ([45.249.212.189]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sZhL7-00000007JH8-339V for linux-arm-kernel@lists.infradead.org; Fri, 02 Aug 2024 01:44:19 +0000 Received: from mail.maildlp.com (unknown [172.19.88.194]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4WZpRM68CGzQngF; Fri, 2 Aug 2024 09:39:43 +0800 (CST) Received: from kwepemi100008.china.huawei.com (unknown [7.221.188.57]) by mail.maildlp.com (Postfix) with ESMTPS id 99A2C140132; Fri, 2 Aug 2024 09:44:04 +0800 (CST) Received: from [10.67.109.254] (10.67.109.254) by kwepemi100008.china.huawei.com (7.221.188.57) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Fri, 2 Aug 2024 09:44:03 +0800 Message-ID: <726da253-9827-b5fe-76ef-99b2ec9c42e3@huawei.com> Date: Fri, 2 Aug 2024 09:44:03 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH] ARM: smp: Fix missing backtrace IPI statics Content-Language: en-US From: Jinjie Ruan To: "Russell King (Oracle)" CC: , , , , , , References: <20240801094022.1402616-1-ruanjinjie@huawei.com> In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.109.254] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemi100008.china.huawei.com (7.221.188.57) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240801_184417_957796_095837EF X-CRM114-Status: GOOD ( 13.80 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2024/8/2 9:39, Jinjie Ruan wrote: > > > On 2024/8/2 0:36, Russell King (Oracle) wrote: >> On Thu, Aug 01, 2024 at 05:40:22PM +0800, Jinjie Ruan wrote: >>> It is similar to ARM64 commit 916b93f4e865 ("arm64: smp: Fix missing IPI >>> statistics"), commit 56afcd3dbd19 ("ARM: Allow IPIs to be handled as normal >>> interrupts") set CPU_BACKTRACE IPI "IRQ_HIDDEN" flag but not show it in >>> show_ipi_list(), which cause the interrupt kstat_irqs accounting >>> is missing in display. >> >> I don't see why this needs to be included. If this IPI fires, it means >> that the kernel has suffered a lockup and is probably not very useful. >> So the chances of being able to read out from /proc/interrupts a non- >> zero "CPU backtrace interrupts" figure is highly unlikely. > > It is more of a change than a bug. > > If we reset the arm32 code to before commit 56afcd3dbd19 ("ARM: Allow > IPIs to be handled as normal interrupts"), the backtrace IPI statics is > shown ok as below, but after that it is missing: Sorry, there is some mistake here, the original result has no backtrace IPI statics. > > / # cat /proc/interrupts > CPU0 > 24: 6 GIC-0 34 Level timer > 25: 469 GIC-0 29 Level twd > 26: 61 GIC-0 75 Edge virtio0 > 29: 8 GIC-0 44 Level kmi-pl050 > 30: 118 GIC-0 45 Level kmi-pl050 > 31: 0 GIC-0 36 Level rtc-pl031 > 32: 0 GIC-0 41 Level mmci-pl18x (cmd) > 33: 0 GIC-0 42 Level mmci-pl18x (pio) > 34: 0 GIC-0 92 Level arm-pmu > 35: 0 GIC-0 93 Level arm-pmu > 36: 0 GIC-0 94 Level arm-pmu > 37: 0 GIC-0 95 Level arm-pmu > 39: 15 GIC-0 37 Level uart-pl011 > IPI0: 0 CPU wakeup interrupts > IPI1: 0 Timer broadcast interrupts > IPI2: 0 Rescheduling interrupts > IPI3: 0 Function call interrupts > IPI4: 0 CPU stop interrupts > IPI5: 0 IRQ work interrupts > IPI6: 0 completion interrupts > IPI7: 0 CPU backtrace interrupts > > >> >> So, I don't see much point to this change. >>