From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E1C92C46467 for ; Wed, 4 Jan 2023 19:11:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235538AbjADTK4 (ORCPT ); Wed, 4 Jan 2023 14:10:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58090 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235053AbjADTKv (ORCPT ); Wed, 4 Jan 2023 14:10:51 -0500 Received: from mail-pj1-x102e.google.com (mail-pj1-x102e.google.com [IPv6:2607:f8b0:4864:20::102e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7CFBF13C; Wed, 4 Jan 2023 11:10:50 -0800 (PST) Received: by mail-pj1-x102e.google.com with SMTP id j8-20020a17090a3e0800b00225fdd5007fso25739336pjc.2; Wed, 04 Jan 2023 11:10:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=fK8KprBXQxaibjIGJr7A7kVu56FVzHtKix4kUO8kSAs=; b=NJlG8WGdeC7Q4YXo/59RTfEw9yVhXncrLSX75zw4rBkNI14uRcJcgrRGP69SX1tJPp noyrbP84oVZiCaL5fwq1Bmlp2nFfEGzhyN5xDhVbsZO4+zH1GxCy8Lx8irYzxVH7iFYS uSLe/kn1o3XeoCFWMbxLqLyN8Ed4VJW2c+ibmwaOOPAJTrrKbCw/yFUL0ZEm1oX/VpGg JpPYVwGLSFzHCTYQfxzAeud2oZC3nQSGjMzH9pnigXIIGbmiOLFuCDlMTBbsXJoRqDm0 nDZQ+LVEFMt+Ewp+H+vc/jAUltzflu/BuWCgWhUMEcpNHg67IelgV8Wiq21RCSzV7S+V ttEw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=fK8KprBXQxaibjIGJr7A7kVu56FVzHtKix4kUO8kSAs=; b=MvNWC8O0GlYHT+YYsgxiAA1304Xx78QqC1f+QF5GvExhYHv7ttqNUjX9cFFy4I3BBb 1DzWQ9colUNGq3G4bs+A1rVjW6XGhKRjVeBYg1uT8vRoT8kvo4uKNzSvjPjgaan5vTSF qKqv3HT2L0mvtqWvnkjE8TXHfojwULVND1Z4iu2KdUFOAQBf/tAipgdX2fm8LGvWYijz vT19Snw0AoCYjpOz65DYc7StDiC2YY9DKXESfzmpyPezovPcDAYAtwycSqkAlHkf+vjm JqSBp5QbD8L8tB4Pc7l5Ep+lKuGzFxwxKTEWlB49pXRb0vAQkWtrg9zatjjkbeOnU3kk 8K4w== X-Gm-Message-State: AFqh2koNNWu1Z9fJARa8PQCQQ9p65ExYzzeAfmCiMWKb+8dwYFk7oxGb aEUeWXKMybfBTuLJwWmuGu8= X-Google-Smtp-Source: AMrXdXsdeR81ha05P/j2pjNtG0ccgLhYd+OEXu4rQp1T43/ufgQ7aGw0qvKNo/bGZegGyE1DPnNzzg== X-Received: by 2002:a05:6a21:3993:b0:b0:2b9c:c11a with SMTP id ad19-20020a056a21399300b000b02b9cc11amr61903988pzc.9.1672859449883; Wed, 04 Jan 2023 11:10:49 -0800 (PST) Received: from [10.67.48.245] ([192.19.223.252]) by smtp.googlemail.com with ESMTPSA id b66-20020a636745000000b0047702d44861sm20353041pgc.18.2023.01.04.11.10.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Jan 2023 11:10:47 -0800 (PST) Message-ID: Date: Wed, 4 Jan 2023 11:10:42 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 Subject: Re: [PATCH v3 0/9] mm: introduce Designated Movable Blocks Content-Language: en-US To: Mel Gorman , Doug Berger Cc: Andrew Morton , Jonathan Corbet , Mike Rapoport , "Paul E. McKenney" , Neeraj Upadhyay , Randy Dunlap , Damien Le Moal , Muchun Song , Vlastimil Babka , Johannes Weiner , Michal Hocko , KOSAKI Motohiro , Mike Kravetz , David Hildenbrand , Oscar Salvador , Joonsoo Kim , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20221020215318.4193269-1-opendmb@gmail.com> <20221026105500.n6ddzqqf5ozjswsp@suse.de> <9842ee9c-5fcc-5458-2779-ad9b88468b48@gmail.com> <20221118170510.kexdiqsfaqwledpm@suse.de> <342da4ea-d04a-996c-85c4-3065dd4dc01f@gmail.com> <20230104153724.mormtuefwaiojvqt@suse.de> From: Florian Fainelli In-Reply-To: <20230104153724.mormtuefwaiojvqt@suse.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/4/23 07:43, Mel Gorman wrote: [snip] >> What is of interest to Broadcom customers is to better distribute user space >> accesses across each memory controller to improve the bandwidth available to >> user space dominated work flows. With no ZONE_MOVABLE, the BCM7278 SoC with >> 1GB of memory on each memory controller will place the 1GB on the low >> address memory controller in ZONE_DMA and the 1GB on the high address memory >> controller in ZONE_NORMAL. With this layout movable allocation requests will >> only fallback to the ZONE_DMA (low memory controller) once the ZONE_NORMAL >> (high memory controller) is sufficiently depleted of free memory. >> >> Adding ZONE_MOVABLE memory above ZONE_NORMAL with the current movablecore >> behavior does not improve this situation other than forcing more kernel >> allocations off of the high memory controller. User space allocations are >> even more likely to be on the high memory controller. >> > > But it's a weak promise that interleaving will happen. If only a portion > of ZONE_MOVABLE is used, it might still be all on the same channel. This > might improve over time if enough memory was used and the system was up > for long enough. It is indeed a weak promise for user-space allocations out of ZONE_MOVABLE, however the other consumer of the DMB region is a kernel driver (typically a video decoder engine) which is directly tied to a specific memory controller/DMB region. For the kernel driver using the DMB region there is a hard guarantee from the kernel that it gets memory from a specific PFN range mapping directly to the desired memory controller and thus it is meeting the desired bandwidth allocation/deadlines/bursts etc. We care about both sides of the coin, though we acknowledge that "controlling" where user-space allocations are coming from such that they be steered towards a specific memory controller is a much harder task and so having some amount of non-determinism is acceptable here. -- Florian