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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 0A0ADD68B26 for ; Thu, 14 Nov 2024 14:12:34 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Xq2Cm32lTz307V; Fri, 15 Nov 2024 01:12:20 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=45.249.212.32 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1731593539; cv=none; b=CcNkQAY68rcy8ZrAlr8NsiXcCnGjUw4yWuAvugRwu3yWValS9MzeHz0pa2Tw/e7e3FGOfsyRaT7z9Cr0a6fzKwo/ndXAGKZXXjIdHxFKEG2JF/8syac7aAmJNM7HQXueK0ticyRbTNdJKUSi/irj8N66LLqV1PSZvBVHV7KK9LO23UhzbPtUsJ6vl1bvQ2AfSDRgoSuhwI5/X7wpnJRiN5BCOeev/2cInnpzw8i/v3vVFzUE8+v/yWx2N7gn9FHVmmbHUOXGbmvhHOLyqwzduvNsV6NnJpdcxStoqbpZC/ex/9ZsoO4pZdyQ3K0rkI1q17Wv8HJKw3bJ6tCv8wLZtQ== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1731593539; c=relaxed/relaxed; bh=+RFQmT0Jk10SYkdEeUrN0TVkwjht9sGn3zQnQWl/evI=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=nMiB0y3XlLWOEraQfe97y1i7B4AdXUHocZxCZIoHTROyTrDqT8z06VCSIQIA2LYtNCeLBYoFDwYiOco+ZyW4OlYNuMCbRjXGg+M0iY/LdAt4wUu0EvpOX1euwgYC5Fif2hrJwKrnvsIVW+QzIwqqLN5zISNGf/UhCRlcHxxM4B2Yk7d1mciV4DA+TLubxxHCBlNzHDbP+Rq5aTjUcDiGKnkfbV4LKDnRXB2XmzIqM6wFUtZJQxKUwaKYM5o4Pio5fhtY/fhhD2OnCuRDsQI8RCU1ZrwFNXBGLAQ+D3dnb5dwErifw1h62Mmhzxouoc7OnC/qj1waItSgRWAyID94Hg== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass (client-ip=45.249.212.32; helo=szxga06-in.huawei.com; envelope-from=yangyicong@huawei.com; receiver=lists.ozlabs.org) smtp.mailfrom=huawei.com Authentication-Results: lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=huawei.com (client-ip=45.249.212.32; helo=szxga06-in.huawei.com; envelope-from=yangyicong@huawei.com; receiver=lists.ozlabs.org) Received: from szxga06-in.huawei.com (szxga06-in.huawei.com [45.249.212.32]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4Xq2Cj5MtZz2xy0 for ; Fri, 15 Nov 2024 01:12:15 +1100 (AEDT) Received: from mail.maildlp.com (unknown [172.19.163.44]) by szxga06-in.huawei.com (SkyGuard) with ESMTP id 4Xq2Cm5V5gz1yqQn; Thu, 14 Nov 2024 22:12:20 +0800 (CST) Received: from kwepemd200014.china.huawei.com (unknown [7.221.188.8]) by mail.maildlp.com (Postfix) with ESMTPS id 004AE1401F4; Thu, 14 Nov 2024 22:12:09 +0800 (CST) Received: from localhost.localdomain (10.50.165.33) by kwepemd200014.china.huawei.com (7.221.188.8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.34; Thu, 14 Nov 2024 22:12:07 +0800 From: Yicong Yang To: , , , , , , , , , , , CC: , , , , , , , , , , , , Subject: [PATCH v9 3/4] arm64: topology: Support SMT control on ACPI based system Date: Thu, 14 Nov 2024 22:11:26 +0800 Message-ID: <20241114141127.23232-4-yangyicong@huawei.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20241114141127.23232-1-yangyicong@huawei.com> References: <20241114141127.23232-1-yangyicong@huawei.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: 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 kwepemd200014.china.huawei.com (7.221.188.8) From: Yicong Yang For ACPI we'll build the topology from PPTT and we cannot directly get the SMT number of each core. Instead using a temporary xarray to record the heterogeneous information (from ACPI_PPTT_ACPI_IDENTICAL) and SMT information of the first core in its heterogeneous CPU cluster when building the topology. Then we can know the largest SMT number in the system. If a homogeneous system's using ACPI 6.2 or later, all the CPUs should be under the root node of PPTT. There'll be only one entry in the xarray and all the CPUs in the system will be assumed identical. The core's SMT control provides two interface to the users [1]: 1) enable/disable SMT by writing on/off 2) enable/disable SMT by writing thread number 1/max_thread_number If a system have more than one SMT thread number the 2) may not handle it well, since there're multiple thread numbers in the system and 2) only accept 1/max_thread_number. So issue a warning to notify the users if such system detected. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/ABI/testing/sysfs-devices-system-cpu#n542 Signed-off-by: Yicong Yang --- arch/arm64/kernel/topology.c | 59 ++++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index 1a2c72f3e7f8..d10ba4b8efee 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -15,8 +15,10 @@ #include #include #include +#include #include #include +#include #include #include @@ -37,17 +39,28 @@ static bool __init acpi_cpu_is_threaded(int cpu) return !!is_threaded; } +struct cpu_smt_info { + int thread_num; + int core_id; +}; + /* * Propagate the topology information of the processor_topology_node tree to the * cpu_topology array. */ int __init parse_acpi_topology(void) { + int max_smt_thread_num = 0; + struct cpu_smt_info *entry; + struct xarray hetero_cpu; + unsigned long hetero_id; int cpu, topology_id; if (acpi_disabled) return 0; + xa_init(&hetero_cpu); + for_each_possible_cpu(cpu) { topology_id = find_acpi_cpu_topology(cpu, 0); if (topology_id < 0) @@ -57,6 +70,32 @@ int __init parse_acpi_topology(void) cpu_topology[cpu].thread_id = topology_id; topology_id = find_acpi_cpu_topology(cpu, 1); cpu_topology[cpu].core_id = topology_id; + + /* + * In the PPTT, CPUs below a node with the 'identical + * implementation' flag have the same number of threads. + * Count the number of threads for only one CPU (i.e. + * one core_id) among those with the same hetero_id. + * See the comment of find_acpi_cpu_topology_hetero_id() + * for more details. + * + * One entry is created for each node having: + * - the 'identical implementation' flag + * - its parent not having the flag + */ + hetero_id = find_acpi_cpu_topology_hetero_id(cpu); + entry = (struct cpu_smt_info *)xa_load(&hetero_cpu, hetero_id); + if (!entry) { + entry = kzalloc(sizeof(*entry), GFP_KERNEL); + WARN_ON(!entry); + + entry->core_id = topology_id; + entry->thread_num = 1; + xa_store(&hetero_cpu, hetero_id, + entry, GFP_KERNEL); + } else if (entry->core_id == topology_id) { + entry->thread_num++; + } } else { cpu_topology[cpu].thread_id = -1; cpu_topology[cpu].core_id = topology_id; @@ -67,6 +106,26 @@ int __init parse_acpi_topology(void) cpu_topology[cpu].package_id = topology_id; } + /* + * This should be a short loop depending on the number of heterogeneous + * CPU clusters. Typically on a homogeneous system there's only one + * entry in the XArray. + */ + xa_for_each(&hetero_cpu, hetero_id, entry) { + if (entry->thread_num != max_smt_thread_num && max_smt_thread_num) + pr_warn_once("Heterogeneous SMT topology is partly supported by SMT control\n"); + + if (entry->thread_num > max_smt_thread_num) + max_smt_thread_num = entry->thread_num; + + xa_erase(&hetero_cpu, hetero_id); + kfree(entry); + } + + if (max_smt_thread_num) + cpu_smt_set_num_threads(max_smt_thread_num, max_smt_thread_num); + + xa_destroy(&hetero_cpu); return 0; } #endif -- 2.24.0