From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from invmail4.hynix.com (exvmail4.hynix.com [166.125.252.92]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 30C8878F4C; Wed, 5 Feb 2025 02:26:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=166.125.252.92 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738722381; cv=none; b=hEwdwVaC25R+uI10H2gZeGSqaEdzilkIBkS0xGXLwlT0NRB0LXzdenGAEZwPPS+Z/m1hLzs9PkFvwgSYIbs4kgU94/u47lJkmZEGgfhgq/MJYJwcT1sLPYPt1PsdA1KW/mGu6fWDQ8OC0Y3hNAsKqMeQEeo3pUmSxUdeptTMDUs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738722381; c=relaxed/simple; bh=oXc3Z/KC1NQ+sl7reJD3khhtese/luU+Yn32+xn6Cio=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=GrFOrBIIAxGFfsImjDQJRDfWPBm19g2rockXhU1qcVe1a0AvBKAWNnOZB2ABGIiKul72KhrU+c/5sSAzYaB5EsuMLI3CSISoRZfkIKlc6JEW1JlnQ1EPh7mggyNrQ6iT7bzicgGmDoeOB6YmfpPR8JYwKjoLEJhvjG7bbFieVSc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com; spf=pass smtp.mailfrom=sk.com; arc=none smtp.client-ip=166.125.252.92 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sk.com X-AuditID: a67dfc5b-3c9ff7000001d7ae-4d-67a2cc3f7de9 Message-ID: <5b9a3776-8661-423a-853f-87fa8b9a7633@sk.com> Date: Wed, 5 Feb 2025 11:26:06 +0900 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: kernel_team@skhynix.com, Joshua Hahn , ying.huang@linux.alibaba.com, rafael@kernel.org, lenb@kernel.org, gregkh@linuxfoundation.org, akpm@linux-foundation.org, rakie.kim@sk.com, dan.j.williams@intel.com, Jonathan.Cameron@huawei.com, dave.jiang@intel.com, horen.chuang@linux.dev, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-mm@kvack.org, kernel-team@meta.com, 42.hyeyoo@gmail.com, Honggyu Kim Subject: Re: [PATCH v4] Weighted Interleave Auto-tuning Content-Language: ko To: Gregory Price References: <20250202141247.2219681-1-joshua.hahnjy@gmail.com> From: Honggyu Kim In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrBIsWRmVeSWpSXmKPExsXC9ZZnoa79mUXpBgcfc1lM7DGwmLN+DZvF 9KkXGC1O3Gxks/h59zi7RfPi9WwWqzf5WszZeYfZ4nb/OVaLVQuvsVkc3zqP3WLfRaCGnQ/f slks39fPaHF51xw2i3tr/rNazP0yldli9ZoMByGPw2/eM3vsnHWX3aO77TK7R8uRt6wei/e8 ZPLYtKqTzWPTp0nsHidm/Gbx2PnQ0mNhw1Rmj/1z17B7nLtY4fF5k1wAbxSXTUpqTmZZapG+ XQJXxp//7gXbBSq+7kxoYDzH08XIySEhYCLRO2cyI4x9a+ldNhCbV8BS4supVjCbRUBF4u36 7+wQcUGJkzOfsIDYogLyEvdvzQCKc3EwC7xnllj0/xZrFyMHh7CAucTX5SogNcwCIhKzO9uY QcIiAqoSbVfcQcqFBGYxStxaMxFsJpuAmsSVl5OYQGxOATOJgyt62CB6zSS6tnYxQtjyEtvf zmEGaZYQOMcucWF2EzPE0ZJADTdYJjAKzkJy3ywku2chmTULyawFjCyrGIUy88pyEzNzTPQy KvMyK/SS83M3MQLjd1ntn+gdjJ8uBB9iFOBgVOLhdWBclC7EmlhWXJl7iFGCg1lJhPf09gXp QrwpiZVVqUX58UWlOanFhxilOViUxHmNvpWnCAmkJ5akZqemFqQWwWSZODilGhiZtsy+wrp8 /5+791d+d/hwwVsp5Y7g1inhavIh3xM/tS7t5bbYdujVca0fMc/qPna7ZuyLaW7dU3Pjxv9P j7p/XZ5aLJmsPvVC0/HVxxdcL/zYw7iQf//Mu+elT3LZbbXZnJF8drFzj5co/8ayAyePPftu fCNgUoy1+e3+qEVZDwUlLzzePHuepxJLcUaioRZzUXEiAIl8UlzbAgAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrBIsWRmVeSWpSXmKPExsXCNUNLT9fuzKJ0g/4b1hYTewws5qxfw2Yx feoFRosTNxvZLH7ePc5u0bx4PZvF6k2+FnN23mG2uN1/jtVi1cJrbBbHt85jt9h3Eajh8NyT rBY7H75ls1i+r5/R4vKuOWwW99b8Z7WY+2Uqs8Wha89ZLVavyXAQ8Tj85j2zx85Zd9k9utsu s3u0HHnL6rF4z0smj02rOtk8Nn2axO5xYsZvFo+dDy09FjZMZfbYP3cNu8e5ixUe3257eCx+ 8YHJ4/MmuQD+KC6blNSczLLUIn27BK6MP//dC7YLVHzdmdDAeI6ni5GTQ0LAROLW0rtsIDav gKXEl1OtYDaLgIrE2/Xf2SHighInZz5hAbFFBeQl7t+aARTn4mAWeM8ssej/LdYuRg4OYQFz ia/LVUBqmAVEJGZ3tjGDhEUEVCXarriDlAsJzGKUuLVmIthMNgE1iSsvJzGB2JwCZhIHV/Sw QfSaSXRt7WKEsOUltr+dwzyBkW8WkjNmIVkxC0nLLCQtCxhZVjGKZOaV5SZm5pjqFWdnVOZl Vugl5+duYgTG57LaPxN3MH657H6IUYCDUYmH14FxUboQa2JZcWXuIUYJDmYlEd7T2xekC/Gm JFZWpRblxxeV5qQWH2KU5mBREuf1Ck9NEBJITyxJzU5NLUgtgskycXBKNTAefs74InNWj+iP /QYdWpfdzH852DcYMEzdtefsxnMTFtybfE+uueBLW0JG8qSZAlbifzcHfJc+PSNuy5ILttc7 b3QyfbvNdTK4YnPCtkXyR7bFzVx3ae/y5wGra2OMl/w62Nld8U7iRfGtLW5m3Un76jU6DFfl LuKaU27TtXmWnrAfo8v5ul+3lViKMxINtZiLihMB67xO2MsCAAA= X-CFilter-Loop: Reflected Hi Gregory, On 2/4/2025 12:38 AM, Gregory Price wrote: > On Mon, Feb 03, 2025 at 09:44:29PM +0900, Honggyu Kim wrote: >> Hi Joshua, >> >>> A node offlining (or even onlining with no new bandwidth information) >>> will just mean that the node inherits whatever value is stored in >>> iw_table at that moment, whether that contains the default values >>> created on init or the last values that it had taken. >> >> It looks the call sequence is as follows. >> >> cxl_region_perf_attrs_callback() >> -> cxl_region_update_coordinates() >> -> node_set_perf_attrs() >> -> mempolicy_set_node_perf() >> -> reduce_interleave_weights() >> >> I haven't searched all the paths of cxl_region_perf_attrs_callback() via >> cxlr->memory_notifier.notifier_call callback pointer, but maybe this >> function is not called when a node is offlined, then I get node >> offlining doesn't trigger re-weight calculation. > > This function is called any time a memory block status changes. > > static int cxl_region_perf_attrs_callback(struct notifier_block *nb, > unsigned long action, void *arg) > { > ... > if (nid == NUMA_NO_NODE || action != MEM_ONLINE) > return NOTIFY_DONE; > ... > } Ah, that's clear now. > > But it doesn't do anything if it's not a call to online a memory block, > so the cached performance data in mempolicy won't change when blocks > are taken offline. > > So the time the scenario you are proposing can arrise is when the device > does not provide performance information (missing CDAT). > > > If a user sets manual mode - they're on the hook to manage everything. > > This is system-wide setting - not a per-task setting. We've yet to see > any strong use-case for individual task weights. If there is a use case > for a task not being subject to system-wide weight changes then it's a > use case for task-local weights. > > ~Gregory Thanks for the explanation. Then except for the nitpicks that I left, I'm fine with this. Thanks, Honggyu