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 X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EE797C04AB6 for ; Mon, 3 Jun 2019 09:05:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D325F27DEF for ; Mon, 3 Jun 2019 09:05:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727471AbfFCJFu (ORCPT ); Mon, 3 Jun 2019 05:05:50 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:46876 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726876AbfFCJFt (ORCPT ); Mon, 3 Jun 2019 05:05:49 -0400 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 6AB3B374; Mon, 3 Jun 2019 02:05:49 -0700 (PDT) Received: from e107155-lin (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2C69F3F690; Mon, 3 Jun 2019 02:05:45 -0700 (PDT) Date: Mon, 3 Jun 2019 10:05:31 +0100 From: Sudeep Holla To: Atish Patra Cc: Jeremy Linton , "linux-kernel@vger.kernel.org" , Mark Rutland , "Rafael J. Wysocki" , "Peter Zijlstra (Intel)" , Catalin Marinas , Linus Walleij , Palmer Dabbelt , Will Deacon , Mauro Carvalho Chehab , "linux-riscv@lists.infradead.org" , Morten Rasmussen , Rob Herring , Anup Patel , Russell King , Ingo Molnar , "devicetree@vger.kernel.org" , Albert Ou , Rob Herring , Paul Walmsley , Thomas Gleixner , "linux-arm-kernel@lists.infradead.org" , Greg Kroah-Hartman , Otto Sabart , Sudeep Holla , "David S. Miller" Subject: Re: [PATCH v6 2/7] dt-binding: cpu-topology: Move cpu-map to a common binding. Message-ID: <20190603090531.GA26487@e107155-lin> References: <20190529211340.17087-1-atish.patra@wdc.com> <20190529211340.17087-3-atish.patra@wdc.com> <0515d803-0da5-dcbe-3d3e-bb786b320d8b@arm.com> <28118149-193d-2a8a-995a-2f1829e95c1c@wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <28118149-193d-2a8a-995a-2f1829e95c1c@wdc.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 03, 2019 at 01:49:13AM -0700, Atish Patra wrote: > On 5/30/19 1:55 PM, Jeremy Linton wrote: > > Hi, > > > > On 5/29/19 4:13 PM, Atish Patra wrote: > > > cpu-map binding can be used to described cpu topology for both > > > RISC-V & ARM. It makes more sense to move the binding to document > > > to a common place. > > > > > > The relevant discussion can be found here. > > > https://lkml.org/lkml/2018/11/6/19 > > > > > > Signed-off-by: Atish Patra > > > Reviewed-by: Sudeep Holla > > > Reviewed-by: Rob Herring > > > --- > > > .../topology.txt => cpu/cpu-topology.txt} | 82 +++++++++++++++---- > > > 1 file changed, 66 insertions(+), 16 deletions(-) > > > rename Documentation/devicetree/bindings/{arm/topology.txt => cpu/cpu-topology.txt} (86%) > > > [...] > > > > > > While socket is optional, its probably a good idea to include the node > > in the example even if the result is the same. > > Sure. I will update that. > > That is because at least > > on arm64 the DT clusters=sockets decision had performance implications > > for larger systems. > > > > Assuring the socket information is correct is helpful by itself to avoid > > having to explain why a single socket machine is displaying some other > > value in lscpu. > > > Just for my understanding, can you give a example? > That's simple. Today any ARM{32,64} DT based platform sets their cluster id to physical package id, which is exposed to userspace. The userspace can/must interpret that as multi-socket system. E.g. TC2/Juno which 2 clusters show up as 2 socket systems which is wrong and needs fixing. We have fixed it for ARM64 ACPI based systems but for DT(mostly used in mobile/embedded) we need to make sure we don't break anything else before we fix it. -- Regards, Sudeep