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 A77A0C3ABCD for ; Mon, 12 May 2025 13:49:41 +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=Nnv01oT6g+VQ6nGPP/GOsGaRFt dNkUdX4mwsnW7VypKqx3qeSCz8zMCLzipr2M1UkFK2fwrOixyPwQ60POjSxSYAp8g1AbrQkkldBsx KqbY98bnd1oyCGGw1VWdGRtxAvn5TbfPUUUHVuG9BBmr5K7HYa6ei/SBxdSrosFwEl+Zc8l6Q0z6o a6rLJMBnr54ytfs0Ru8wc9+KYV8sxAg3MwOkS6xVrga7zFVtW+cqY9SwkNi87g1RI6L5WqM7FghqC gMxE6suxRKXdHGFVtOxt5qBS+8exmiKponr29HGPD33RygiBnI/7DOk2bH8Q+cPinxahYPGd/rgVH 7CqbLNVQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uETXD-00000009cEz-2LCL; Mon, 12 May 2025 13:49:35 +0000 Received: from szxga02-in.huawei.com ([45.249.212.188]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uESue-00000009UU8-3SyJ for linux-arm-kernel@lists.infradead.org; Mon, 12 May 2025 13:09:47 +0000 Received: from mail.maildlp.com (unknown [172.19.163.48]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4Zx0GB4xF0zQkSL; Mon, 12 May 2025 21:05:38 +0800 (CST) Received: from dggemv712-chm.china.huawei.com (unknown [10.1.198.32]) by mail.maildlp.com (Postfix) with ESMTPS id 8F0CF1800B2; Mon, 12 May 2025 21:09:38 +0800 (CST) Received: from kwepemq200018.china.huawei.com (7.202.195.108) by dggemv712-chm.china.huawei.com (10.1.198.32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Mon, 12 May 2025 21:09:38 +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; Mon, 12 May 2025 21:09:37 +0800 From: Yicong Yang To: , , , , , , , , , CC: , , , , Subject: [PATCH v2 2/2] arm64/watchdog_hld: Add a cpufreq notifier for update watchdog thresh Date: Mon, 12 May 2025 21:09:19 +0800 Message-ID: <20250512130919.23915-3-yangyicong@huawei.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20250512130919.23915-1-yangyicong@huawei.com> References: <20250512130919.23915-1-yangyicong@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.50.165.33] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) 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-20250512_060945_178927_A6DBDC0B X-CRM114-Status: GOOD ( 12.97 ) 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