From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm2-f13.google.com (mail-wm2-f13.google.com [74.125.225.141]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E9EAC4CDA08 for ; Wed, 30 Sep 2026 12:03:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.225.141 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790769838; cv=none; b=ew5YMYVcPQgKsjt+FskDoTRJ+ZkrcbyUjbydlFxX7tkTo5oCsdVQbMRPWfa/DA7PBNv4oWAZLgmzAItSXeUDr88V0hugLnBiQADngJ5iTf47L87eDuiTu4LTeso0aiSNIbdwrT9ICqSR+5dWxvYMFElUckxZWiXamtHLrFfyKbk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790769838; c=relaxed/simple; bh=nva1a+1N6OMLgAq4Mh9QV/dIao63usjnuzDRG/nvAX0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=IMHJaJaVtnYWL5JeYjnN3qM5c52ZsXf2aG3FLnCyqeQXjquz0L9HbZSm39GIurBfdoIFkst4AGMVbWaz8mIueD+iuTzCwgD5R6cIAWlheGDbzerKJZ3GtcEGALm9jVpr95m4a6OiobrOFtaxdsWiVTX6UZjVrbrMS6s4UNtqplQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=gourry.net; spf=pass smtp.mailfrom=gourry.net; dkim=pass (2048-bit key) header.d=gourry.net header.i=@gourry.net header.b=AQa4NDex; arc=none smtp.client-ip=74.125.225.141 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=gourry.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gourry.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gourry.net header.i=@gourry.net header.b="AQa4NDex" Received: by mail-wm2-f13.google.com with SMTP id 5b1f17b1804b1-49fe8bf173aso27888505e9.3 for ; Wed, 30 Sep 2026 05:03:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gourry.net; s=google; t=1790769835; x=1791374635; darn=vger.kernel.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=wdi3drddBXh2MbeE/kE5oeEb6Dfood/saqLoKtI29Z8=; b=AQa4NDexJGaxWiOsHFP0LXqY67EQtobPzOMTq9kSSCtqNlaReFElg7Q4X70JTWxTNe CdV+Mc29UtPTYEDwi/N9Pqzi+YhQn1aMDkiivLiCGxlLrYO+zxd/0LYBNCiBD/MFaBZV kKP6+OP5t1/RuLUgvOcWBW5tHDvlGf5KVLeeuWpbYfyHah3aXMHx+i/CNS9A6JbcR08p ix5vu7OnXOC+7KqucQTpSquVm9qkjcKs1dBY37GdNY36iUhrM0UiKbTjVCKBwhnRC2Zz 2R0uIBKyzYODZ1p5gvcz4KdVxSuKYuYvDEdYn7kRXhP6ys/IVB0ADgMO8Gl0yxzg1XFU /tBg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790769835; x=1791374635; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=wdi3drddBXh2MbeE/kE5oeEb6Dfood/saqLoKtI29Z8=; b=CKUIoxQ1/6o+M0XX/acQo1VLxmCk0G6aSHcZlAlsZAY9jjpChzE/W4iSjC/tFEhRwp fQ8lVd3mJ2P29EwT9ZkUGwcYRVmRaYB3l/SpcFpzjhY8h1wbu2gPSO+MfLTdjez/0fS6 BuM2ZsS3rln6E0sN4i27TB61oWt19U8dpB3S0umESRQlrM0j34EukASolZwf+Ow572aC FLTRYo3V5giVjNBxV0ABr0GMY8o6w+pYvQ98nC8OfQ2fIzNBIua8cxcTsjEh8zcbbEkR OirfOKGp8E+TwgwTFALTzp4/XKUmYMTi2ojeVABN+9665xXtZp3mRTl/zNA9BjGBHfHw x3EA== X-Forwarded-Encrypted: i=1; AKwUvByOk4+Wk0OlOPv3cdOe0Dg03qUQ5x8UGBW940sBQ+hFAlZNFPFb2c5B9Uqttf4lw98/vh2naxMawK6yHro=@vger.kernel.org X-Gm-Message-State: AFuF++l12+3HsWy46EzZKsZ6yot3H2h6OJlkrUTlIXMc4VyVhnpSE4be fj40BN2zBGfVZg09YOyED+xith0WzpWf/f1EtR2l9ir47a8Yt41WCBsynw+LJ5zIHrM= X-Gm-Gg: AYBFou19uTqEeKQQ8PTMBNVTaiFIRceE955dqPG/Qi/MxNQH48nuSa7o1Y8hB3juVaZ 2MML31V1+pJYnbGtlIA8iodF1Sx+U6Lp/MoxQxUjStbjn7/JIymy8j5nLqpAVJVmiuJOKxp8X4E DND1AemQ0kOwVFIWXdt2pULuMMLRkMEMXbuVCxf137JM7Z+xwMnL+/QBw0ujjNo7HuZ3hQXBiVr bnLYIqNycsJPKIZ2y8r/uOqSeQ2bQxkIyLHE9b9MqZDd6k01WZYx9jLHqoLhZJbifbuJMot3ko2 w/iGZn8EIcuwq+ukLZbf5K26UEGA5ScqP5nHHZa75MexRDkq7oXE/nZpjOoIk7x8aKrl5ZsNUfK 9tJfVZW4QZn6XZkkOBYpas1tipi0pO6LWjaZspQst0m7e3aRW/Nb4g6FcregCz0d5P6quYBwJpi Wd23LAStNlfj/tSfhtfH4tkE+Z5msMvM4A61kLQ99FdWmsv4rdhYzPLakTOJZtfn3HYF4= X-Received: by 2002:a05:600c:8a16:10b0:4a0:b9:21b5 with SMTP id 5b1f17b1804b1-4a01b12cbcemr15861675e9.30.1790769835112; Wed, 30 Sep 2026 05:03:55 -0700 (PDT) Received: from gourry-fedora-PF4VCD3F ([2620:10d:c092:500::6:13b8]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a017468b10sm66347925e9.0.2026.09.30.05.03.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Sep 2026 05:03:54 -0700 (PDT) Date: Wed, 30 Sep 2026 08:03:52 -0400 From: Gregory Price To: "David Hildenbrand (Arm)" Cc: Li Zhe , akpm@linux-foundation.org, ljs@kernel.org, liam@infradead.org, rppt@kernel.org, mhocko@suse.com, corbet@lwn.net, skhan@linuxfoundation.org, ziy@nvidia.com, joshua.hahnjy@gmail.com, ying.huang@linux.alibaba.com, apopple@nvidia.com, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/numa_balancing: allow migrate on protnone reference with MPOL_WEIGHTED_INTERLEAVE policy Message-ID: References: <20260930072617.64665-1-lizhe.67@bytedance.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: On Wed, Sep 30, 2026 at 01:26:17PM +0200, David Hildenbrand (Arm) wrote: > > > > Initial placement is only a starting point. Pages initially allocated on > > fast memory are not necessarily the long-term hot pages, and pages > > initially allocated on slower memory may become hot as the workload's hot > > set changes. The policy therefore needs to be able to combine weighted > > initial placement with memory tiering's NUMA fault based hot-page > > promotion. > > Ok, so memory allocation will respect the weights but balancing will ignore > them? That really sounds rather odd to me. > > And I assume that was the reason why we might have disallowed the combination: > it turns a weighted mechanism into an unweighted mechanism. > > So are we really sure these semantics that you would essentially set in stone > here are the semantics we want? (ignoring weights) > Right, but you're requesting this configuration. If you didn't set F_NUMA_BALANCING then you get the existing semantics. In the existing semantics, if we're INTERLEAVE and WEIGHTED_INTERLEAVE we just always say "no tiering for you". But as an opt-in option? I don't quite see the argument for saying interleaved regions (or tasks) to be opted-out if the user asks for it - that just seems like an arbitrary limitation. ~Gregory