From patchwork Wed Nov 7 17:13:44 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sudeep Holla X-Patchwork-Id: 150440 Delivered-To: patch@linaro.org Received: by 2002:a2e:299d:0:0:0:0:0 with SMTP id p29-v6csp5421119ljp; Wed, 7 Nov 2018 09:13:56 -0800 (PST) X-Google-Smtp-Source: AJdET5ff6IZns2TiArP4gl/dOtkBcY3aEfoplkMlmOPIpePYAas1LGb0T3MpVLDg0tEw9MkMwcVC X-Received: by 2002:a62:995c:: with SMTP id d89-v6mr1011481pfe.11.1541610836122; Wed, 07 Nov 2018 09:13:56 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1541610836; cv=none; d=google.com; s=arc-20160816; b=dKHRZcZt2jgB0lQ4iHgutMfk9KxkN73wsF9DthkxgZ8a/6PIUHgTLqooOhw4r+HsEG ExUdtBMRLzw+adynj7DTpG6r+LnsGyiJg/u3KKv37F0FLbScQmEO0t45WDoivKjk8Dk2 vXzjJnWEnHy0yEG80bG8pa8ACTdBHn+xrybxIRLdsVtCaaNkIFD/oF2O4zqpt07vfsOM RHz1sZhQRqnxtkfSX2VMWNePTQl9zrskZ1EJmH2RftG+khLtHrZ9aRiAUyuSqEM3F4qv Q3BMK1JoIabhK5iLSQHLi2fd0hWRCQqxvwBzS5nR2WCqCUa/Es0qsj4nYitleVBQXhYN DOOQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:message-id:date:subject:cc:to:from; bh=axu4fyezYFs2ecWA8Y9wseCyGvoMNBJeZL3Ag63xHEI=; b=I3yQQGh0hLRCYoTCDrMGZbdvKknSC4nuCHBh58oQ6kePqI3NEv0tkEhFVUhZ4cpzJS YpJbn/+K1reOvxYhut5xX4C10wjAGr2jhIEIRQIY5y4XtZD1zSrgyCyOCBztrDxSLG1B MCcLP2JXHhsfqGhz7YVj+DXh33VQCadj6K+Lg/EyZrOYZqpSKyyw8ANvoGePWGexN6KC Ds9sbwv5ahlYKQDeekItb6LpU9QKiO3fNztjgv7eDYoL1HCe1rFtKLDeHSwqegdihGES IhAVR7W6C1n6D/2D6cTeut7mg4hU6aXjz9oA05MS5OX/IlliRXIvd9wxpaAsxqsCbZEo DMNw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of devicetree-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=devicetree-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id j14si1052568pgi.354.2018.11.07.09.13.55; Wed, 07 Nov 2018 09:13:56 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of devicetree-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of devicetree-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=devicetree-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727630AbeKHCpL (ORCPT + 6 others); Wed, 7 Nov 2018 21:45:11 -0500 Received: from foss.arm.com ([217.140.101.70]:55122 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727772AbeKHCpL (ORCPT ); Wed, 7 Nov 2018 21:45:11 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 53535A78; Wed, 7 Nov 2018 09:13:54 -0800 (PST) Received: from usa.arm.com (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 40A8D3F5CF; Wed, 7 Nov 2018 09:13:52 -0800 (PST) From: Sudeep Holla To: robh+dt@kernel.org, devicetree@vger.kernel.org Cc: Sudeep Holla , linux-kernel@vger.kernel.org, palmer@sifive.com, anup@brainfault.org, Damien.LeMoal@wdc.com, mick@ics.forth.gr, atish.patra@wdc.com, mark.rutland@arm.com, zong@andestech.com, alankao@andestech.com Subject: [RFC PATCH] Documentation: DT: arm: add support for sockets defining package boundaries Date: Wed, 7 Nov 2018 17:13:44 +0000 Message-Id: <20181107171344.983-1-sudeep.holla@arm.com> X-Mailer: git-send-email 2.17.1 Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org The current ARM DT topology description provides the operating system with a topological view of the system that is based on leaf nodes representing either cores or threads (in an SMT system) and a hierarchical set of cluster nodes that creates a hierarchical topology view of how those cores and threads are grouped. However this hierarchical representation of clusters does not allow to describe what topology level actually represents the physical package or the socket boundary, which is a key piece of information to be used by an operating system to optimize resource allocation and scheduling. Lets add a new "socket" node type in the cpu-map node to describe the same. Signed-off-by: Sudeep Holla --- .../devicetree/bindings/arm/topology.txt | 52 ++++++++++++++----- 1 file changed, 39 insertions(+), 13 deletions(-) (Note patch generated with -b option to avoid 60+ of whitespace changes) Hi Rob, You had expressed your interest to generalise the CPU topology bindings accross multiple architectures. Do you want to move to the generic bindings before adding this $subject socket support or is it OK to finalise on this and then move the majority(based on the agreement) to generic binding. Regards, Sudeep -- 2.17.1 diff --git a/Documentation/devicetree/bindings/arm/topology.txt b/Documentation/devicetree/bindings/arm/topology.txt index de9eb0486630..668483554cca 100644 --- a/Documentation/devicetree/bindings/arm/topology.txt +++ b/Documentation/devicetree/bindings/arm/topology.txt @@ -9,6 +9,7 @@ ARM topology binding description In an ARM system, the hierarchy of CPUs is defined through three entities that are used to describe the layout of physical CPUs in the system: +- socket - cluster - core - thread @@ -63,21 +64,23 @@ nodes are listed. The cpu-map node's child nodes can be: - - one or more cluster nodes + - one or more cluster nodes or + - one or more socket nodes in a multi-socket system Any other configuration is considered invalid. -The cpu-map node can only contain three types of child nodes: +The cpu-map node can only contain 4 types of child nodes: +- socket node - cluster node - core node - thread node whose bindings are described in paragraph 3. -The nodes describing the CPU topology (cluster/core/thread) can only -be defined within the cpu-map node and every core/thread in the system -must be defined within the topology. Any other configuration is +The nodes describing the CPU topology (socket/cluster/core/thread) can +only be defined within the cpu-map node and every core/thread in the +system must be defined within the topology. Any other configuration is invalid and therefore must be ignored. =========================================== @@ -85,26 +88,44 @@ invalid and therefore must be ignored. =========================================== cpu-map child nodes must follow a naming convention where the node name -must be "clusterN", "coreN", "threadN" depending on the node type (ie -cluster/core/thread) (where N = {0, 1, ...} is the node number; nodes which -are siblings within a single common parent node must be given a unique and +must be "socketN", "clusterN", "coreN", "threadN" depending on the node type +(ie socket/cluster/core/thread) (where N = {0, 1, ...} is the node number; nodes +which are siblings within a single common parent node must be given a unique and sequential N value, starting from 0). cpu-map child nodes which do not share a common parent node can have the same name (ie same number N as other cpu-map child nodes at different device tree levels) since name uniqueness will be guaranteed by the device tree hierarchy. =========================================== -3 - cluster/core/thread node bindings +3 - socket/cluster/core/thread node bindings =========================================== -Bindings for cluster/cpu/thread nodes are defined as follows: +Bindings for socket/cluster/cpu/thread nodes are defined as follows: + +- socket node + + Description: must be declared within a cpu-map node, one node + per physical socket in the system. A system can + contain single or multiple physical socket. + The association of sockets and NUMA nodes is beyond + the scope of this bindings, please refer [2] for + NUMA bindings. + + This node is optional for a single socket system. + + The socket node name must be "socketN" as described in 2.1 above. + A socket node can not be a leaf node. + + A socket node's child nodes must be one or more cluster nodes. + + Any other configuration is considered invalid. - cluster node Description: must be declared within a cpu-map node, one node per cluster. A system can contain several layers of - clustering and cluster nodes can be contained in parent - cluster nodes. + clustering within a single physical socket and cluster + nodes can be contained in parent cluster nodes. The cluster node name must be "clusterN" as described in 2.1 above. A cluster node can not be a leaf node. @@ -164,13 +185,15 @@ levels) since name uniqueness will be guaranteed by the device tree hierarchy. 4 - Example dts =========================================== -Example 1 (ARM 64-bit, 16-cpu system, two clusters of clusters): +Example 1 (ARM 64-bit, 16-cpu system, two clusters of clusters in a single +physical socket): cpus { #size-cells = <0>; #address-cells = <2>; cpu-map { + socket0 { cluster0 { cluster0 { core0 { @@ -253,6 +276,7 @@ cpus { }; }; }; + }; CPU0: cpu@0 { device_type = "cpu"; @@ -473,3 +497,5 @@ cpus { =============================================================================== [1] ARM Linux kernel documentation Documentation/devicetree/bindings/arm/cpus.txt +[2] Devicetree NUMA binding description + Documentation/devicetree/bindings/numa.txt