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 55D7FC7115B for ; Thu, 19 Jun 2025 15:46:13 +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-Type: Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-ID:Date :Subject:CC:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Jau7W3b9/JXouEyI4iGFtD0OrKxc29Z8qTaIT9su0Kw=; b=FYjxktAeuXst+eCviAO/MbI49c r58iuSmWNvAr+7RyuP2ao3Bucxuf/rWSvXh9B1gRH30osbsvR7wSmV/pn0CteCVQ2I3pGsjsaQm6Y Tz0gq7Td+BF58hbxZK5LMknNF53Q1tKucI07awEgX2PiqNIWuJtxlqvbP0HNIP9X0NV6GRK4URmPQ pbwkM5dNc4dz/ASM97wjKgfyhrBxjkt8LbQoSJfLwFMgEa4sM9/f5tWI1RsXJ3mS5gcV8oNaIYAe6 MmZ8boekghIzMm6P9eR6lTyTCmTEjr9g9o2I0ldf6ZVFHt46/m6xqNhA57tRPx5ajCaKh5Ltns3X6 Z9zfjhog==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uSHSk-0000000DTUF-2E0V; Thu, 19 Jun 2025 15:46:02 +0000 Received: from szxga04-in.huawei.com ([45.249.212.190]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uSDkk-0000000CwUH-2knh for linux-arm-kernel@lists.infradead.org; Thu, 19 Jun 2025 11:48:24 +0000 Received: from mail.maildlp.com (unknown [172.19.163.17]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4bNJjb3LdLz2TSs2; Thu, 19 Jun 2025 19:46:43 +0800 (CST) Received: from dggemv705-chm.china.huawei.com (unknown [10.3.19.32]) by mail.maildlp.com (Postfix) with ESMTPS id 31EE81A0188; Thu, 19 Jun 2025 19:48:13 +0800 (CST) Received: from kwepemq200018.china.huawei.com (7.202.195.108) by dggemv705-chm.china.huawei.com (10.3.19.32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Thu, 19 Jun 2025 19:48:12 +0800 Received: from localhost.localdomain (10.50.165.33) by kwepemq200018.china.huawei.com (7.202.195.108) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Thu, 19 Jun 2025 19:48:12 +0800 From: Yicong Yang To: , , , , , , , , , CC: , , , , Subject: [RESEND PATCH v2 2/2] arm64/watchdog_hld: Add a cpufreq notifier for update watchdog thresh Date: Thu, 19 Jun 2025 19:48:05 +0800 Message-ID: <20250619114805.16968-3-yangyicong@huawei.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20250619114805.16968-1-yangyicong@huawei.com> References: <20250619114805.16968-1-yangyicong@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.50.165.33] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To kwepemq200018.china.huawei.com (7.202.195.108) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250619_044822_996642_FDEBFEEC X-CRM114-Status: GOOD ( 13.14 ) 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 From: Yicong Yang arm64 depends on the cpufreq driver to gain the maximum cpu frequency to convert the watchdog_thresh to perf event period. cpufreq drivers like cppc_cpufreq will be initialized lately after the initializing of the hard lockup detector so just use a safe cpufreq which will be inaccurency. Use a cpufreq notifier to adjust the event's period to a more accurate one. Signed-off-by: Yicong Yang --- arch/arm64/kernel/watchdog_hld.c | 58 ++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) diff --git a/arch/arm64/kernel/watchdog_hld.c b/arch/arm64/kernel/watchdog_hld.c index dcd25322127c..e55548cb26df 100644 --- a/arch/arm64/kernel/watchdog_hld.c +++ b/arch/arm64/kernel/watchdog_hld.c @@ -34,3 +34,61 @@ bool __init arch_perf_nmi_is_available(void) */ return arm_pmu_irq_is_nmi(); } + +static int watchdog_perf_update_period(void *data) +{ + int cpu = raw_smp_processor_id(); + u64 max_cpu_freq, new_period; + + max_cpu_freq = cpufreq_get_hw_max_freq(cpu) * 1000UL; + if (!max_cpu_freq) + return 0; + + new_period = watchdog_thresh * max_cpu_freq; + hardlockup_detector_perf_adjust_period(cpu, new_period); + + return 0; +} + +static int watchdog_freq_notifier_callback(struct notifier_block *nb, + unsigned long val, void *data) +{ + struct cpufreq_policy *policy = data; + int cpu; + + if (val != CPUFREQ_CREATE_POLICY) + return NOTIFY_DONE; + + /* + * Let each online CPU related to the policy update the period by their + * own. This will serialize with the framework on start/stop the lockup + * detector (softlockup_{start,stop}_all) and avoid potential race + * condition. Otherwise we may have below theoretical race condition: + * (core 0/1 share the same policy) + * [core 0] [core 1] + * hardlockup_detector_event_create() + * hw_nmi_get_sample_period() + * (cpufreq registered, notifier callback invoked) + * watchdog_freq_notifier_callback() + * watchdog_perf_update_period() + * (since core 1's event's not yet created, + * the period is not set) + * perf_event_create_kernel_counter() + * (event's period is SAFE_MAX_CPU_FREQ) + */ + for_each_cpu(cpu, policy->cpus) + smp_call_on_cpu(cpu, watchdog_perf_update_period, NULL, false); + + return NOTIFY_DONE; +} + +static struct notifier_block watchdog_freq_notifier = { + .notifier_call = watchdog_freq_notifier_callback, +}; + +static int __init init_watchdog_freq_notifier(void) +{ + return cpufreq_register_notifier(&watchdog_freq_notifier, + CPUFREQ_POLICY_NOTIFIER); +} +core_initcall(init_watchdog_freq_notifier); -- 2.24.0