From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-131.freemail.mail.aliyun.com (out30-131.freemail.mail.aliyun.com [115.124.30.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 773F2374E72; Thu, 12 Mar 2026 09:42:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773308545; cv=none; b=G8Fi3psLE6I0lx86xyUK+IbWZm+TN3agft1E2RQlRr1KligeZowC313Jo8UHrGYf83AgL1O2iVgf7+8VkUmklvW48nmwOxALX8PvWZ+wtOobymDDBtMbkVvLo9h1iLYm3vLPPn4dtJRodQ+Ykc+ngEY5gERSApCDAcEzbeX8wZg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773308545; c=relaxed/simple; bh=ocIyzr7c1RNiy8C07Am4OL8gIKsCyYLoB2MPmXZ0htM=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=BZTOGs6l/Pwk5s761EdJ1SY06AbaUBZ4rpWYyCL8RcPTUOKXNJwdZKV6nA282T1rMDKr3oJRcdNyFBl+AmfRPsKcIslRssxDJCK9sPz2cT1l+Dnw+cylKlTfAhH16IZnfm15VBRSRu0QcWeK1hDNnsjxfrHN2kaS/S6SWFnAxpk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=SOy/gILo; arc=none smtp.client-ip=115.124.30.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="SOy/gILo" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1773308535; h=From:To:Subject:Date:Message-ID:MIME-Version:Content-Type; bh=yPWlaauP5LfYdgi3W21fsz1vO9uleriWqeR2AsRR+/U=; b=SOy/gILofrVSdvOsnJcUH8152kPoVWdiglqIq+MblDpUkvdXrVUDQhSczD7jStytoWubL5xTFPNrDlL+ceR2xbjQpwUjv1L+krvNVsuOVqpTwEVwBF+0oJeXLqmoy17xuI52ZyHtxtbwt9J4yNqHLdZxehzqvQswwMiMFakkbT4= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033045098064;MF=ying.huang@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0X-oES69_1773308534; Received: from DESKTOP-5N7EMDA(mailfrom:ying.huang@linux.alibaba.com fp:SMTPD_---0X-oES69_1773308534 cluster:ay36) by smtp.aliyun-inc.com; Thu, 12 Mar 2026 17:42:15 +0800 From: "Huang, Ying" To: YeeLi Cc: akpm@linux-foundation.org, david@kernel.org, dan.j.williams@intel.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 In-Reply-To: <20260312091207.2016518-1-seven.yi.lee@gmail.com> (YeeLi's message of "Thu, 12 Mar 2026 17:12:07 +0800") References: <20260312091207.2016518-1-seven.yi.lee@gmail.com> Date: Thu, 12 Mar 2026 17:42:13 +0800 Message-ID: <878qbxpeoa.fsf@DESKTOP-5N7EMDA> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ascii YeeLi writes: > From: yeeli > > Automatic tuning for weighted interleaving [1] provides real benefits on > systems with CXL support. However, platforms that lack HMAT or CDAT > information cannot make use of this feature. > > 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. > > This patch introduces an optional Kconfig option, > CONFIG_NUMA_BW_MANUAL_OVERRIDE (default n), which exposes node bandwidth > R/W sysfs attributes under: > > /sys/kernel/mm/mempolicy/weighted_interleave/bw_nodeN > > The sysfs files are created and removed dynamically on node hotplug > events, in sync with the existing weighted_interleave/nodeN attributes. > > 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. How to use this new interface? Can you provide an example? --- Best Regards, Huang, Ying > [1] Link: > https://lkml.kernel.org/r/20250505182328.4148265-1-joshua.hahnjy@gmail.com > [snip]