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b=Kl67e94Udq+FYSBQax5dPA1xjM/jAjGZRM10EB7dJSNVnEgoPm5INRkbAjUckC92GpsK8B89wcJqY2Xu8UMqi19ivkM+PwWMVSIvdUstqF04WlzQ/p+YSPdtvvuq+20Dqjs5J0ohInbuTyuxJSJewyEOfXnmCew+4pAEJd4u3Eg= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from DS5PPFA3734E4BA.namprd12.prod.outlook.com (2603:10b6:f:fc00::65c) by DS7PR12MB5887.namprd12.prod.outlook.com (2603:10b6:8:7a::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9846.16; Tue, 21 Apr 2026 22:04:28 +0000 Received: from DS5PPFA3734E4BA.namprd12.prod.outlook.com ([fe80::d03f:ffac:bea5:143c]) by DS5PPFA3734E4BA.namprd12.prod.outlook.com ([fe80::d03f:ffac:bea5:143c%6]) with mapi id 15.20.9818.017; Tue, 21 Apr 2026 22:04:28 +0000 Message-ID: <9d8a18da-14e4-4d90-a224-7d69d4daeb13@amd.com> Date: Tue, 21 Apr 2026 17:04:24 -0500 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 00/16] fs,x86/resctrl: Add kernel-mode (e.g., PLZA) support to the resctrl subsystem To: Reinette Chatre , Babu Moger , "corbet@lwn.net" , "tony.luck@intel.com" , "Dave.Martin@arm.com" , "james.morse@arm.com" , "tglx@kernel.org" , "mingo@redhat.com" , "bp@alien8.de" , "dave.hansen@linux.intel.com" Cc: "skhan@linuxfoundation.org" , "x86@kernel.org" , "hpa@zytor.com" , "peterz@infradead.org" , "juri.lelli@redhat.com" , "vincent.guittot@linaro.org" , "dietmar.eggemann@arm.com" , "rostedt@goodmis.org" , "bsegall@google.com" , "mgorman@suse.de" , "vschneid@redhat.com" , "kas@kernel.org" , "rick.p.edgecombe@intel.com" , "akpm@linux-foundation.org" , "pmladek@suse.com" , "rdunlap@infradead.org" , "dapeng1.mi@linux.intel.com" , "kees@kernel.org" , "elver@google.com" , "paulmck@kernel.org" , "lirongqing@baidu.com" , "safinaskar@gmail.com" , "fvdl@google.com" , "seanjc@google.com" , "pawan.kumar.gupta@linux.intel.com" , "xin@zytor.com" , "tiala@microsoft.com" , "chang.seok.bae@intel.com" , "Lendacky, Thomas" , "elena.reshetova@intel.com" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-coco@lists.linux.dev" , "kvm@vger.kernel.org" , "eranian@google.com" , "peternewman@google.com" References: <43880b7b-b390-4e7f-8c2a-46cde9e3b051@intel.com> <5a273b0f-8225-4e9e-924e-884183734659@intel.com> <73c46024-4cf2-4f03-9268-d4378825fa87@amd.com> <973067bf-6e6c-446a-a81a-713840d701a9@intel.com> <90f4a692-1c27-4967-bf12-ec3cb597681d@amd.com> <68a551ea-d9f0-436a-9bef-e35fd027bb95@intel.com> <39e0c786-cc35-4555-bfb9-ff7cd758c423@amd.com> <99a2da36-6a21-4a99-98e0-3c9a4cf7ecf6@amd.com> <741aa53e-461c-4a1a-a701-6060d42012f8@intel.com> <71099958-1ddf-40dc-8a3c-aa13d0c56fee@intel.com> <8d969f11-4a7f-4e36-b85a-c3ed714fc603@intel.com> <0334ba64-71b3-40bd-8cce-9f0f119e7dc9@intel.com> Content-Language: en-US From: "Moger, Babu" In-Reply-To: Content-Type: text/plain; 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If I understand correctly >>>>> above default scenario essentially means "inherit_ctrl_and_mon" but instead of adding it to this file >>>>> we will need to add documentation that describes to user space how this file should be interpreted. >>>>> It seems easier to me to just be clear via info/kernel_mode itself on what the current active mode is? >>>>> >>>>> I think something like below will be more intuitive and not need much additional >>>>> documentation to understand (I am just adding the "uninitialized" as an example to match text >>>>> printed in schemata file during pseudo-locking ... even if there is a group named "uninitialized" >>>>> the lack of "/" could be used to make it clear what this means?): >>>>> >>>>>      # cat info/kernel_mode >>>>>      [inherit_ctrl_and_mon] >>>>>      global_assign_ctrl_assign_mon_per_cpu:group=uninitialized >>>>>      global_assign_ctrl_inherit_mon_per_cpu:group=uninitialized >>>>> > > Above I share considerations when thinking whether to keep "inherit_ctrl_and_mon" or not ... > >>>> >>>> Sounds ok to me. > > ... to which you seem to agree ... > >>>> >>>> >>>>> I also think an interface like this would be simpler for user space to use as it (user space) switches >>>>> between PLZA capable and non-PLZA capable systems since user space need not associate existence of >>>>> the file with some kernel mode state in addition to actual content of the file when it does exist. > > > ... more considerations from me when thinking whether to keep "inherit_ctrl_and_mon" or not ... My bad. My only motivation was to keep the mode listing display consistent. That said, I agree we need to support this. Without it, we won’t be able to move the group from PLZA to non-PLZA. # cat info/kernel_mode inherit_ctrl_and_mon: global_assign_ctrl_assign_mon_per_cpu:group=uninitialized [global_assign_ctrl_assign_mon_per_cpu]:group=ctrl1/mon1/ # echo "inherit_ctrl_and_mon:group=ctrl1/mon1/" > info/kernel_mode # cat info/kernel_mode inherit_ctrl_and_mon: global_assign_ctrl_assign_mon_per_cpu:group=uninitialized [global_assign_ctrl_assign_mon_per_cpu]:group=uninitialized Thanks Babu