From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 42B8825785D; Tue, 16 Dec 2025 20:24:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765916683; cv=none; b=t5aAGIsA5aX0HKg9p1+ufk0q73BWId5FRmWWH537mpIQ40Q8vFB7mSePmfkqozMBKeNIlwxRFazbgkmbUuKpmi87GYZdU3oeHD4qWUZmoV58WKPyibm0NqfHi5pOCCAqYxDgRNfx36VsD8JmUerTNPDx8x0gaNt9m4gyC0LTN6o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765916683; c=relaxed/simple; bh=ycv7no2r0HogxUiULI/OFg8qd8I2bXxi6V1PqZaAaKk=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=HyOYwQHJdixvkuxZEhx1Ctkozbq6R2ebpMUucdSDcS8ps7K490KRXnOxNDljU82+VNi2Oq5RJjeHbAfjoAAVZtSblMIyvDbkBQCArxzddCApTJAh8z8Tg3ZJR75hy6dbh6qKzi2darexhK0fYlARUxS/o0sIf5GlZ2eDGDQFolg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=rzS9hdJi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="rzS9hdJi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34DEEC4CEF1; Tue, 16 Dec 2025 20:24:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1765916682; bh=ycv7no2r0HogxUiULI/OFg8qd8I2bXxi6V1PqZaAaKk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=rzS9hdJiYKkF5jy6MSgIR8HlM3FIDA5F6SVzhIqgOpqDJ6MZkA57rhcPmGQxPC08Z wmS5ly+0puFtohUYi0O+DrA6bWEPmE9JRp+lkOig5st+Xb6XFSDkLn2DD4Lmzv+DMR 9zvxeeh2FL+1w1BiI/eD9LhObmcLQgRqTga0xW7U= Date: Tue, 16 Dec 2025 12:24:41 -0800 From: Andrew Morton To: Akinobu Mita Cc: linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, hannes@cmpxchg.org, david@kernel.org, mhocko@kernel.org, zhengqi.arch@bytedance.com, shakeel.butt@linux.dev, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com Subject: Re: [PATCH 1/2] mm: memory-tiers, numa_emu: enable to create memory tiers using fake numa nodes Message-Id: <20251216122441.2810043bbc51621315e3862c@linux-foundation.org> In-Reply-To: <20251208094028.214949-2-akinobu.mita@gmail.com> References: <20251208094028.214949-1-akinobu.mita@gmail.com> <20251208094028.214949-2-akinobu.mita@gmail.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) 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-Transfer-Encoding: 7bit On Mon, 8 Dec 2025 18:40:27 +0900 Akinobu Mita wrote: > This makes it possible to create memory tiers using fake numa nodes > generated by numa emulation. > > The new "numa_emulation.adistance" kernel parameter allows you to set the > abstract distance for each NUMA node. > > For example, if the system is booted with the parameters > "numa=fake=2 numa_emulation.adistance=576,704", it will configure memory > tiers with node0 having the default DRAM adistance value and node1 having > a lower adistance value. Confusing. I'd have thought that this commandline would gave node0 a distance of 576 and node1 a distance of 704? But the text talks about some third "default" distance, of unknown value. Can we please clear all this up? Also, we have little documentation for this stuff. fake-numa-for-cpusets.rst and kernel-parameters.txt. Can you please find somewhere appropriate to document this new user-facing feature? Maybe a new Documentation file?