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=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,RCVD_ILLEGAL_IP,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 3708DC2D0C4 for ; Wed, 11 Dec 2019 03:04:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 16DA72077B for ; Wed, 11 Dec 2019 03:04:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727459AbfLKDEt (ORCPT ); Tue, 10 Dec 2019 22:04:49 -0500 Received: from mga09.intel.com ([134.134.136.24]:34882 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726619AbfLKDEs (ORCPT ); Tue, 10 Dec 2019 22:04:48 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Dec 2019 19:04:48 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,301,1571727600"; d="scan'208";a="215772928" Received: from shzintpr04.sh.intel.com (HELO [0.0.0.0]) ([10.239.4.101]) by orsmga003.jf.intel.com with ESMTP; 10 Dec 2019 19:04:46 -0800 Subject: Re: [PATCH] ACPI/HMAT: Fix the parsing of Cache Associativity and Write Policy From: Tao Xu To: "Rafael J. Wysocki" Cc: Rafael Wysocki , Len Brown , Greg Kroah-Hartman , Dan Williams , Dave Hansen , ACPI Devel Maling List , Linux Kernel Mailing List References: <20191202070348.32148-1-tao3.xu@intel.com> <6dbcdaff-feae-68b9-006d-dd8aec032553@intel.com> <0e4219c3-943a-e416-e5eb-723bed8c9383@intel.com> <82e7361e-256e-002c-6b30-601cec1fad07@intel.com> Message-ID: <0f8084fd-86a9-081c-e32a-20c756c9daf6@intel.com> Date: Wed, 11 Dec 2019 11:04:45 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <82e7361e-256e-002c-6b30-601cec1fad07@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/10/19 9:18 PM, Tao Xu wrote: > On 12/10/2019 4:27 PM, Rafael J. Wysocki wrote: >> On Tue, Dec 10, 2019 at 9:19 AM Tao Xu wrote: >>> >>> On 12/10/2019 4:06 PM, Rafael J. Wysocki wrote: >>>> On Tue, Dec 10, 2019 at 2:04 AM Tao Xu wrote: >>>>> >>>>> On 12/9/2019 6:01 PM, Rafael J. Wysocki wrote: >>>>>> On Mon, Dec 2, 2019 at 8:03 AM Tao Xu wrote: >>>>>>> >>>>>>> In chapter 5.2.27.5, Table 5-147: Field "Cache Attributes" of >>>>>>> ACPI 6.3 spec: 0 is "None", 1 is "Direct Mapped", 2 is "Complex >>>>>>> Cache >>>>>>> Indexing" for Cache Associativity; 0 is "None", 1 is "Write Back", >>>>>>> 2 is "Write Through" for Write Policy. >>>>>> >>>>>> Well, I'm not sure what the connection between the above statement, >>>>>> which is correct AFAICS, and the changes made by the patch is. >>>>>> >>>>>> Is that the *_OTHER symbol names are confusing or something deeper? >>>>>> >>>>> >>>>> Because in include/acpi/actbl1.h: >>>>> >>>>> #define ACPI_HMAT_CA_NONE                     (0) >>>>> >>>>> ACPI_HMAT_CA_NONE is 0, but in include/linux/node.h: >>>>> >>>>>       enum cache_indexing { >>>>>              NODE_CACHE_DIRECT_MAP, >>>>>              NODE_CACHE_INDEXED, >>>>>              NODE_CACHE_OTHER, >>>>>       }; >>>>> NODE_CACHE_OTHER is 2, and for otner enum: >>>>> >>>>>             case ACPI_HMAT_CA_DIRECT_MAPPED: >>>>>                     tcache->cache_attrs.indexing = >>>>> NODE_CACHE_DIRECT_MAP; >>>>>                     break; >>>>>             case ACPI_HMAT_CA_COMPLEX_CACHE_INDEXING: >>>>>                     tcache->cache_attrs.indexing = NODE_CACHE_INDEXED; >>>>>                     break; >>>>> in include/acpi/actbl1.h: >>>>> >>>>>     #define ACPI_HMAT_CA_DIRECT_MAPPED            (1) >>>>>     #define ACPI_HMAT_CA_COMPLEX_CACHE_INDEXING   (2) >>>>> >>>>> but in include/linux/node.h: >>>>> >>>>> NODE_CACHE_DIRECT_MAP is 0, NODE_CACHE_INDEXED is 1. This is >>>>> incorrect. >>>> >>>> Why is it incorrect? >>> >>> Sorry I paste the wrong pre-define. >>> >>> This is the incorrect line: >>> >>> case ACPI_HMAT_CA_DIRECT_MAPPED: >>> tcache->cache_attrs.indexing = NODE_CACHE_DIRECT_MAP; >>> >>> ACPI_HMAT_CA_DIRECT_MAPPED is 1, NODE_CACHE_DIRECT_MAP is 0. That means >>> if HMAT table input 1 for cache_attrs.indexing, kernel store 0 in >>> cache_attrs.indexing. But in ACPI 6.3, 0 means "None". So for the whole >>> switch codes: >> >> This is a mapping between the ACPI-defined values and the generic ones >> defined in the kernel.  There is not rule I know of by which they must >> be the same numbers.  Or is there such a rule which I'm missing? >> >> As long as cache_attrs.indexing is used consistently going forward, >> the difference between the ACPI-defined numbers and its values >> shouldn't matter, should it? >> > Yes, it will not influence the ACPI HMAT tables. Only influence is the > sysfs, as in > https://www.kernel.org/doc/html/latest/admin-guide/mm/numaperf.html: > > # tree sys/devices/system/node/node0/memory_side_cache/ > /sys/devices/system/node/node0/memory_side_cache/ > |-- index1 > |   |-- indexing > |   |-- line_size > |   |-- size > |   `-- write_policy > > indexing is parsed in this file, so it can be read by user-space. > Although now there is no user-space tool use this information to do some > thing. But I am wondering if it is used in the future, someone use it to > show the memory side cache information to user or use it to do > performance turning. I finish a test using emulated ACPI HMAT from QEMU (branch:hmat https://github.com/taoxu916/qemu.git) And I get the kernel log and sysfs output: [ 0.954288] HMAT: Cache: Domain:0 Size:20480 Attrs:00081111 SMBIOS Handles:0 [ 0.954835] HMAT: Cache: Domain:1 Size:15360 Attrs:00081111 SMBIOS Handles:0 /sys/devices/system/node/node0/memory_side_cache/index1 # cat indexing 0 /sys/devices/system/node/node0/memory_side_cache/index1 # cat write_policy 0 Note that 'Attrs' is printed using %x, so we can get: (attrs & ACPI_HMAT_CACHE_ASSOCIATIVITY) >> 8 = 1, (attrs & ACPI_HMAT_WRITE_POLICY) >> 12 = 1 but we get 0 in sysfs, so if user or software read this information and read the ACPI 6.3 spec, will think there is 'none' for Cache Associativity or Write Policy. p.s. the qemu input CLI: ./x86_64-softmmu/qemu-system-x86_64 \ -machine pc,hmat=on -nographic \ -kernel ./bzImage \ -initrd ./initramfs-virt \ -append console=ttyS0 \ -m 2G \ -smp 2,sockets=2 \ -object memory-backend-ram,size=1G,id=m0 \ -object memory-backend-ram,size=1G,id=m1 \ -numa node,nodeid=0,memdev=m0 \ -numa node,nodeid=1,memdev=m1,initiator=0 \ -numa cpu,node-id=0,socket-id=0 \ -numa cpu,node-id=0,socket-id=1 \ -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=20 \ -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \ -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=65 \ -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \ -numa hmat-cache,node-id=0,size=20K,level=1,associativity=direct,policy=write-back,line=8 \ -numa hmat-cache,node-id=1,size=15K,level=1,associativity=direct,policy=write-back,line=8