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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 61F90C433B4 for ; Tue, 20 Apr 2021 03:31:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1C63D613AE for ; Tue, 20 Apr 2021 03:31:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229579AbhDTDb3 convert rfc822-to-8bit (ORCPT ); Mon, 19 Apr 2021 23:31:29 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]:2886 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229508AbhDTDb3 (ORCPT ); Mon, 19 Apr 2021 23:31:29 -0400 Received: from fraeml745-chm.china.huawei.com (unknown [172.18.147.200]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4FPTbH46gdz70gKj; Tue, 20 Apr 2021 11:25:31 +0800 (CST) Received: from lhreml717-chm.china.huawei.com (10.201.108.68) by fraeml745-chm.china.huawei.com (10.206.15.226) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 20 Apr 2021 05:30:56 +0200 Received: from dggemi761-chm.china.huawei.com (10.1.198.147) by lhreml717-chm.china.huawei.com (10.201.108.68) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2176.2; Tue, 20 Apr 2021 04:30:55 +0100 Received: from dggemi761-chm.china.huawei.com ([10.9.49.202]) by dggemi761-chm.china.huawei.com ([10.9.49.202]) with mapi id 15.01.2176.012; Tue, 20 Apr 2021 11:30:53 +0800 From: "Song Bao Hua (Barry Song)" To: Greg KH , Jonathan Cameron CC: "tim.c.chen@linux.intel.com" , "catalin.marinas@arm.com" , "will@kernel.org" , "rjw@rjwysocki.net" , "vincent.guittot@linaro.org" , "bp@alien8.de" , "tglx@linutronix.de" , "mingo@redhat.com" , "lenb@kernel.org" , "peterz@infradead.org" , "dietmar.eggemann@arm.com" , "rostedt@goodmis.org" , "bsegall@google.com" , "mgorman@suse.de" , "msys.mizuma@gmail.com" , "valentin.schneider@arm.com" , "juri.lelli@redhat.com" , "mark.rutland@arm.com" , "sudeep.holla@arm.com" , "aubrey.li@linux.intel.com" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "x86@kernel.org" , "xuwei (O)" , "Zengtao (B)" , "guodong.xu@linaro.org" , yangyicong , "Liguozhu (Kenneth)" , "linuxarm@openeuler.org" , "hpa@zytor.com" , "tiantao (H)" Subject: RE: [RFC PATCH v5 1/4] topology: Represent clusters of CPUs within a die Thread-Topic: [RFC PATCH v5 1/4] topology: Represent clusters of CPUs within a die Thread-Index: AQHXHHeQcl1lHq1u7kWPO6cWrdJxq6qKVPyAgACJR5D//6lPAIAAByuAgDJgJ6A= Date: Tue, 20 Apr 2021 03:30:53 +0000 Message-ID: <57660c1863194dd58e441fce9d5d1580@hisilicon.com> References: <20210319041618.14316-1-song.bao.hua@hisilicon.com> <20210319041618.14316-2-song.bao.hua@hisilicon.com> <20210319093616.00001879@Huawei.com> In-Reply-To: Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.126.200.79] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org > -----Original Message----- > From: Greg KH [mailto:gregkh@linuxfoundation.org] > Sent: Friday, March 19, 2021 11:02 PM > To: Jonathan Cameron > Cc: Song Bao Hua (Barry Song) ; > tim.c.chen@linux.intel.com; catalin.marinas@arm.com; will@kernel.org; > rjw@rjwysocki.net; vincent.guittot@linaro.org; bp@alien8.de; > tglx@linutronix.de; mingo@redhat.com; lenb@kernel.org; peterz@infradead.org; > dietmar.eggemann@arm.com; rostedt@goodmis.org; bsegall@google.com; > mgorman@suse.de; msys.mizuma@gmail.com; valentin.schneider@arm.com; > juri.lelli@redhat.com; mark.rutland@arm.com; sudeep.holla@arm.com; > aubrey.li@linux.intel.com; linux-arm-kernel@lists.infradead.org; > linux-kernel@vger.kernel.org; linux-acpi@vger.kernel.org; x86@kernel.org; > xuwei (O) ; Zengtao (B) ; > guodong.xu@linaro.org; yangyicong ; Liguozhu (Kenneth) > ; linuxarm@openeuler.org; hpa@zytor.com > Subject: Re: [RFC PATCH v5 1/4] topology: Represent clusters of CPUs within > a die > > On Fri, Mar 19, 2021 at 09:36:16AM +0000, Jonathan Cameron wrote: > > On Fri, 19 Mar 2021 06:57:08 +0000 > > "Song Bao Hua (Barry Song)" wrote: > > > > > > -----Original Message----- > > > > From: Greg KH [mailto:gregkh@linuxfoundation.org] > > > > Sent: Friday, March 19, 2021 7:35 PM > > > > To: Song Bao Hua (Barry Song) > > > > Cc: tim.c.chen@linux.intel.com; catalin.marinas@arm.com; > will@kernel.org; > > > > rjw@rjwysocki.net; vincent.guittot@linaro.org; bp@alien8.de; > > > > tglx@linutronix.de; mingo@redhat.com; lenb@kernel.org; > peterz@infradead.org; > > > > dietmar.eggemann@arm.com; rostedt@goodmis.org; bsegall@google.com; > > > > mgorman@suse.de; msys.mizuma@gmail.com; valentin.schneider@arm.com; > Jonathan > > > > Cameron ; juri.lelli@redhat.com; > > > > mark.rutland@arm.com; sudeep.holla@arm.com; aubrey.li@linux.intel.com; > > > > linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org; > > > > linux-acpi@vger.kernel.org; x86@kernel.org; xuwei (O) > ; > > > > Zengtao (B) ; guodong.xu@linaro.org; > yangyicong > > > > ; Liguozhu (Kenneth) ; > > > > linuxarm@openeuler.org; hpa@zytor.com > > > > Subject: Re: [RFC PATCH v5 1/4] topology: Represent clusters of CPUs within > > > > a die > > > > > > > > On Fri, Mar 19, 2021 at 05:16:15PM +1300, Barry Song wrote: > > > > > diff --git a/Documentation/admin-guide/cputopology.rst > > > > b/Documentation/admin-guide/cputopology.rst > > > > > index b90dafc..f9d3745 100644 > > > > > --- a/Documentation/admin-guide/cputopology.rst > > > > > +++ b/Documentation/admin-guide/cputopology.rst > > > > > @@ -24,6 +24,12 @@ core_id: > > > > > identifier (rather than the kernel's). The actual value is > > > > > architecture and platform dependent. > > > > > > > > > > +cluster_id: > > > > > + > > > > > + the Cluster ID of cpuX. Typically it is the hardware platform's > > > > > + identifier (rather than the kernel's). The actual value is > > > > > + architecture and platform dependent. > > > > > + > > > > > book_id: > > > > > > > > > > the book ID of cpuX. Typically it is the hardware platform's > > > > > @@ -56,6 +62,14 @@ package_cpus_list: > > > > > human-readable list of CPUs sharing the same physical_package_id. > > > > > (deprecated name: "core_siblings_list") > > > > > > > > > > +cluster_cpus: > > > > > + > > > > > + internal kernel map of CPUs within the same cluster. > > > > > + > > > > > +cluster_cpus_list: > > > > > + > > > > > + human-readable list of CPUs within the same cluster. > > > > > + > > > > > die_cpus: > > > > > > > > > > internal kernel map of CPUs within the same die. > > > > > > > > Why are these sysfs files in this file, and not in a Documentation/ABI/ > > > > file which can be correctly parsed and shown to userspace? > > > > > > Well. Those ABIs have been there for much a long time. It is like: > > > > > > [root@ceph1 topology]# ls > > > core_id core_siblings core_siblings_list physical_package_id > thread_siblings thread_siblings_list > > > [root@ceph1 topology]# pwd > > > /sys/devices/system/cpu/cpu100/topology > > > [root@ceph1 topology]# cat core_siblings_list > > > 64-127 > > > [root@ceph1 topology]# > > > > > > > > > > > Any chance you can fix that up here as well? > > > > > > Yes. we will send a separate patch to address this, which won't > > > be in this patchset. This patchset will base on that one. > > > > > > > > > > > Also note that "list" is not something that goes in sysfs, sysfs is "one > > > > value per file", and a list is not "one value". How do you prevent > > > > overflowing the buffer of the sysfs file if you have a "list"? > > > > > > > > > > At a glance, the list is using "-" rather than a real list > > > [root@ceph1 topology]# cat core_siblings_list > > > 64-127 > > > > > > Anyway, I will take a look if it has any chance to overflow. > > > > It could in theory be alternate CPUs as comma separated list. > > So it's would get interesting around 500-1000 cpus (guessing). > > > > Hopefully no one has that crazy a cpu numbering scheme but it's possible > > (note that cluster is fine for this, but I guess it might eventually > > happen for core-siblings list (cpus within a package). > > > > Shouldn't crash or anything like that but might terminate early. > > We have a broken sysfs api already for listing LED numbers that has had > to be worked around in the past, please do not create a new one with > that same problem, we should learn from them :) Another place I am seeing a cpu list is in numa topology: /sys/devices/system/node/nodex/cpulist. But the code has a BUILD_BUG_ON to guard the pagebuf: static ssize_t node_read_cpumap(struct device *dev, bool list, char *buf) { ssize_t n; cpumask_var_t mask; struct node *node_dev = to_node(dev); /* 2008/04/07: buf currently PAGE_SIZE, need 9 chars per 32 bits. */ BUILD_BUG_ON((NR_CPUS/32 * 9) > (PAGE_SIZE-1)); if (!alloc_cpumask_var(&mask, GFP_KERNEL)) return 0; cpumask_and(mask, cpumask_of_node(node_dev->dev.id), cpu_online_mask); n = cpumap_print_to_pagebuf(list, buf, mask); free_cpumask_var(mask); return n; } For lists in cpu topology, I haven't seen this while I believe we need it. Or am I missing something? > > thanks, > > greg k-h Thanks Barry