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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-50939e8e0ecsm35572931cf.5.2026.03.12.09.12.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Mar 2026 09:12:37 -0700 (PDT) Date: Thu, 12 Mar 2026 12:12:35 -0400 From: Gregory Price To: YeeLi Cc: akpm@linux-foundation.org, david@kernel.org, dan.j.williams@intel.com, ying.huang@linux.alibaba.com, linux-mm@kvack.org, joshua.hahnjy@gmail.com, linux-kernel@vger.kernel.org, Jonathan.Cameron@huawei.com, linux-cxl@vger.kernel.org, dave.jiang@intel.com Subject: Re: [PATCH] mm/mempolicy: add sysfs interface to override NUMA node bandwidth Message-ID: References: <20260312091207.2016518-1-seven.yi.lee@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260312091207.2016518-1-seven.yi.lee@gmail.com> X-Rspam-User: X-Rspamd-Queue-Id: 4C1BB1C000D X-Rspamd-Server: rspam08 X-Stat-Signature: 1fnzgimrfpj6jtq787o3y7xjfnsrqdey X-HE-Tag: 1773331959-723183 X-HE-Meta: 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 XiQO3bQb 7p2hvCFfDLTyshKl+Po9+hAA7TVPixLpEvoBeW3/LRnO/6KOgQ79EmsjA53NjTK0RgqoDvtQEk5aS5V7PsxAxfHoODLbCKCqrjF577XsiGJXvqnBROR3d5ZHcTWYO3BNLSsYrgmvKVHCQB1pQ9wCfkn/WiEQ3Zl+UjXvZUDOESVgeUiFGVLU+d9mwpH+1KMie4ldI5IBSKmXOm5u+Sufl411WGXBYu5nNpal2EKPfwLCgUBMSaf2Y2DKJQU5um9w2hxERYlS1pXqY7fwPiTuKLd7/64xCSTPWo/3/Pbo9fHNG4piM1eWmaq6qpqpmAeZq4um/gLV2TDERvCUux//v+kdYYc/vLDacof+8ywQxOSMjb+XLTMbM9QnMdaA6YCxF3I2pIFDoNmltzx+/FxaJcEQVMeeSk1v5SaWdS2PTC2FieDw= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Mar 12, 2026 at 05:12:07PM +0800, YeeLi wrote: > From: yeeli > > If the bandwidth reported by firmware or the device deviates from the > actual measured bandwidth, administrators also lack a clear way to adjust > the per-node weight values. > If userland is setting the raw bandwidth stat, why can't they do a tiny bit of math to figure out the preferred weighting and just write the weights? > > Userspace can write a single bandwidth value (in MB/s) to override both > read_bandwidth and write_bandwidth for the corresponding NUMA node. The > value is then propagated to the internal node_bw_table via > mempolicy_set_node_perf(). > > This interface is intended for debugging and experimentation only. > Should be posted as [RFC] then, I don't think we want this upstream. ~Gregory