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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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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> 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