From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id EC0EA37CD42 for ; Thu, 16 Jul 2026 16:22:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784218937; cv=none; b=XtH29nJiqsN7QKYFZxarzzbHuMTf5fmtfaJhbsJpO/yVtg7utvB5TkSEKW1czIglqp0JrkwMz9QrJU8aLDdK3ETp/KIwHQx17o3I443tMNbZjxzgnAlPqoW4z3ecaMcNWFIGE/MGJER/PtBagS45+HdBBtsMrZxVvf1F6mDvgZ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784218937; c=relaxed/simple; bh=hWSX/oWmJJ2P+WFvv/FZYBpnQpjV1MoTqYXHcDiefn4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=kQaqKxUIg7k5KuYs7znAA2eOtQCe8CTZ6SiMxOnJvcsXKyN4qOAMxgj4mMxUZc4CdLylj62ZsYh/FvPDmXVydUyNQ5qKoGnbQjqMj+gYdqbl7P/wZeKy5x8n3z3CQobXxNAHaMydF+06ikYgfqpILGKOjXyiZNnET8BSxBtNlAs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=BKzzE8DE; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="BKzzE8DE" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 19E562F; Thu, 16 Jul 2026 09:22:10 -0700 (PDT) Received: from [10.2.212.8] (e134344.arm.com [10.2.212.8]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BBC7B3F7B4; Thu, 16 Jul 2026 09:22:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1784218934; bh=hWSX/oWmJJ2P+WFvv/FZYBpnQpjV1MoTqYXHcDiefn4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=BKzzE8DE91XXy7mX5vrwogs3ix/b+AOi7onAZmuaC6NcY4qNVs9z4MPleSYO616la yoAOtMUiiAOlPKbAOQfm7T1L9LxBjua3P+TTLKN9Wipp0ZxipwaGCUqWsE9hNGdBQ7 x5H6Pz6hzAa8N6nrs3+4uJy4HaDrXV8imC0Fs6KM= Message-ID: <0300fd4a-7c21-4f72-8e6c-ab98e0cc7c58@arm.com> Date: Thu, 16 Jul 2026 17:22:11 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Thunderbird Daily Subject: Re: [RFC] mpam,x86,fs/resctrl: Generic schema description Proof of Concept To: "Luck, Tony" , "Chatre, Reinette" , Fenghua Yu , James Morse , Dave Martin , Babu Moger , Drew Fustini , "Chen, Yu C" Cc: Borislav Petkov , Thomas Gleixner , Dave Hansen , Peter Newman , "x86@kernel.org" , "linux-kernel@vger.kernel.org" References: <5ee87762-1898-4b62-94da-85b3e9917ecc@intel.com> <62701203-c4a3-4ec2-a9af-602e1fc15863@nvidia.com> <8f9f78dd-e3f5-4b35-bc72-0eb5dafdcedf@nvidia.com> <36163a81-9737-49e3-93ef-6c392f7272f0@intel.com> <0fc6df54-26c7-43fa-948a-528cd94937f1@arm.com> <9049378c-699a-4155-b1e4-737a1d7265d5@intel.com> <57740b97-80ee-4632-bca3-dc43cd7776c2@arm.com> Content-Language: en-US From: Ben Horgan In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Tony, On 7/16/26 17:02, Luck, Tony wrote: >>> This was one element of original discussion that fizzled a bit since it was not obvious that user >>> space would behave like this. Consider, for example, from Documentation/filesystems/resctrl.rst: >>> >>> Reading/writing the schemata file >>> --------------------------------- >>> ... When writing you only need to specify those values which you wish to change. .. >> >> Yeah, I don't know but it does seem like something a user could reasonably expect to work. > > Personally I use one of two options to update schemata: > > 1) Just want to change something small: > # echo "MB:1=50" > schemata > 2) I want to make global change to some resource > # vi schemata > on L2 line: s/ffff/ff/g > :wq > > In case 2 every domain on every resource is written, but most of them to the existing value. We've got a user :) > > This may need careful consideration if the legacy "MB" lines are present together with the > new controls for MIN, MAX etc. > > Having a mode file to select whether legacy OR native controls are exposed would avoid > a lot of complexity in the kernel. Yes, that would mean a user that wants to use the new > native interface must add one "echo" to some startup script. > > Or perhaps yet another "rdt=" command line option to pick whether mount defaults to > legacy or native mode? The "rdt=" options are x86 specific so I don't think we should use them for generic resctrl. A mount option might be end up being convenient. Thanks, Ben > > -Tony