From patchwork Tue Mar 11 07:51:41 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yicong Yang X-Patchwork-Id: 14011246 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 5153BC28B2E for ; Tue, 11 Mar 2025 07:59:10 +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=rIHv27FelkoCdY23L+zoRCxdo2m98WIDi578UXcHqno=; b=eSoq541+Nx/bdLXzTiwpLAmcAl GiR/p/zEx0jPxqB61qufHVF3m8N/EY/KdIZD/a06fZsvlmBg6Kxkf9Lrkd3Gg35UnPlAVVFW0lAUc dGWaVKtEMlgmyV7o2Ia3+GVPJbr+bA+LazlCLDtttfuOqyTuPz8oBvNB0gc1t/d1TG3ky8KLhSv+j lKDmAkrwUc4dVrfTJLRyFqaHxp7CWh7KgWYgpIK9Z7FPW1uDcZP0Cl7cLo4IXicq0lkJ5p6Y9pPbV p4pJErKUegtTyCjpq6ZwhaUE6Cd6YRBDxjhV0or4U4sEx1dTH0TFfZQNu5awJk3uTOSdNc1Jc4Krd W8AxCU7g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1truVv-00000004vTB-11NJ; Tue, 11 Mar 2025 07:58:59 +0000 Received: from szxga04-in.huawei.com ([45.249.212.190]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1truP8-00000004uR5-3U3Z for linux-arm-kernel@lists.infradead.org; Tue, 11 Mar 2025 07:52:00 +0000 Received: from mail.maildlp.com (unknown [172.19.163.44]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4ZBm7h0CXBz2RTR0; Tue, 11 Mar 2025 15:47:28 +0800 (CST) Received: from kwepemd200014.china.huawei.com (unknown [7.221.188.8]) by mail.maildlp.com (Postfix) with ESMTPS id 27B0F1402CD; Tue, 11 Mar 2025 15:51:48 +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; Tue, 11 Mar 2025 15:51:47 +0800 From: Yicong Yang To: , , , , , , , , , , , CC: , , , , , , , , , , , , , Subject: [PATCH v12 2/4] arch_topology: Support SMT control for OF based system Date: Tue, 11 Mar 2025 15:51:41 +0800 Message-ID: <20250311075143.61078-3-yangyicong@huawei.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20250311075143.61078-1-yangyicong@huawei.com> References: <20250311075143.61078-1-yangyicong@huawei.com> MIME-Version: 1.0 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) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250311_005159_181128_0DC68E77 X-CRM114-Status: GOOD ( 15.58 ) 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 On building the topology from the devicetree, we've already gotten the SMT thread number of each core. Update the largest SMT thread number and enable the SMT control by the end of topology parsing. The framework's SMT control provides two interface to the users [1] through /sys/devices/system/cpu/smt/control: 1) enable SMT by writing "on" and disable by "off" 2) enable SMT by writing max_thread_number or disable by writing 1 Both method support to completely disable/enable the SMT cores so both work correctly for symmetric SMT platform and asymmetric platform with non-SMT and one type SMT cores like: core A: 1 thread core B: X (X!=1) threads Note that for a theoretically possible multiple SMT-X (X>1) core platform the SMT control is also supported as expected but only by writing the "on/off" method. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/ABI/testing/sysfs-devices-system-cpu#n542 Reviewed-by: Pierre Gondois Reviewed-by: Dietmar Eggemann Signed-off-by: Yicong Yang Reviewed-by: Sudeep Holla --- drivers/base/arch_topology.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c index 3ebe77566788..d409d323ee64 100644 --- a/drivers/base/arch_topology.c +++ b/drivers/base/arch_topology.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -506,6 +507,10 @@ core_initcall(free_raw_capacity); #endif #if defined(CONFIG_ARM64) || defined(CONFIG_RISCV) + +/* Used to enable the SMT control */ +static unsigned int max_smt_thread_num = 1; + /* * This function returns the logic cpu number of the node. * There are basically three kinds of return values: @@ -565,6 +570,8 @@ static int __init parse_core(struct device_node *core, int package_id, i++; } while (1); + max_smt_thread_num = max_t(unsigned int, max_smt_thread_num, i); + cpu = get_cpu_for_node(core); if (cpu >= 0) { if (!leaf) { @@ -677,6 +684,17 @@ static int __init parse_socket(struct device_node *socket) if (!has_socket) ret = parse_cluster(socket, 0, -1, 0); + /* + * Reset the max_smt_thread_num to 1 on failure. Since on failure + * we need to notify the framework the SMT is not supported, but + * max_smt_thread_num can be initialized to the SMT thread number + * of the cores which are successfully parsed. + */ + if (ret) + max_smt_thread_num = 1; + + cpu_smt_set_num_threads(max_smt_thread_num, max_smt_thread_num); + return ret; }