From patchwork Tue Jun 8 09:13:14 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mike Rapoport X-Patchwork-Id: 12305967 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A10EAC48BCF for ; Tue, 8 Jun 2021 09:14:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7CD3261208 for ; Tue, 8 Jun 2021 09:14:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231534AbhFHJQX (ORCPT ); Tue, 8 Jun 2021 05:16:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:34754 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231474AbhFHJQI (ORCPT ); Tue, 8 Jun 2021 05:16:08 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 15D1F61208; Tue, 8 Jun 2021 09:14:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1623143655; bh=ABj3dtzcvKeBeFBwlP7EY29yWmF1bk7z4ehtK6n5siY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=stUgf4ZUN/ZjSy3cddYB2cZIaHTQz0UInwhnxlWhOMvCMB3022bIGbC4rI3NrqrM1 QmLL+dj7le7GZlEIRctc2Holu8sBQ4hBKr4bteOorCCiBykhRXnFqCe5zGJPpsRhNx aZ7Yk9zICQGNTe5pituUg0Ba4N2fsfS9qPtf7uH2YMSxoOUzntozTcXnNItAhSKlTD U9/aWrwxnhFl721/M+eLG5WZnWTlaajb4bQOcN5cBlcR7fTMpFaJkpCQNR2hBfCift xxQCcQDtiZxWODdp0mQ7waEcvJVWzGCOEhvz4CYn53e9Gj8n8Rw/qWs1u1YIGfcTO7 QsagSKZFkKehA== From: Mike Rapoport To: Andrew Morton Cc: Arnd Bergmann , Geert Uytterhoeven , Ivan Kokshaysky , Jonathan Corbet , Matt Turner , Mike Rapoport , Mike Rapoport , Richard Henderson , Vineet Gupta , kexec@lists.infradead.org, linux-alpha@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-xtensa@linux-xtensa.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org Subject: [PATCH v3 7/9] docs: remove description of DISCONTIGMEM Date: Tue, 8 Jun 2021 12:13:14 +0300 Message-Id: <20210608091316.3622-8-rppt@kernel.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20210608091316.3622-1-rppt@kernel.org> References: <20210608091316.3622-1-rppt@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org From: Mike Rapoport Remove description of DISCONTIGMEM from the "Memory Models" document and update VM sysctl description so that it won't mention DISCONIGMEM. Signed-off-by: Mike Rapoport --- Documentation/admin-guide/sysctl/vm.rst | 12 +++---- Documentation/vm/memory-model.rst | 45 ++----------------------- 2 files changed, 8 insertions(+), 49 deletions(-) diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst index 586cd4b86428..ddbd71d592e0 100644 --- a/Documentation/admin-guide/sysctl/vm.rst +++ b/Documentation/admin-guide/sysctl/vm.rst @@ -936,12 +936,12 @@ allocations, THP and hugetlbfs pages. To make it sensible with respect to the watermark_scale_factor parameter, the unit is in fractions of 10,000. The default value of -15,000 on !DISCONTIGMEM configurations means that up to 150% of the high -watermark will be reclaimed in the event of a pageblock being mixed due -to fragmentation. The level of reclaim is determined by the number of -fragmentation events that occurred in the recent past. If this value is -smaller than a pageblock then a pageblocks worth of pages will be reclaimed -(e.g. 2MB on 64-bit x86). A boost factor of 0 will disable the feature. +15,000 means that up to 150% of the high watermark will be reclaimed in the +event of a pageblock being mixed due to fragmentation. The level of reclaim +is determined by the number of fragmentation events that occurred in the +recent past. If this value is smaller than a pageblock then a pageblocks +worth of pages will be reclaimed (e.g. 2MB on 64-bit x86). A boost factor +of 0 will disable the feature. watermark_scale_factor diff --git a/Documentation/vm/memory-model.rst b/Documentation/vm/memory-model.rst index ce398a7dc6cd..30e8fbed6914 100644 --- a/Documentation/vm/memory-model.rst +++ b/Documentation/vm/memory-model.rst @@ -14,15 +14,11 @@ for the CPU. Then there could be several contiguous ranges at completely distinct addresses. And, don't forget about NUMA, where different memory banks are attached to different CPUs. -Linux abstracts this diversity using one of the three memory models: -FLATMEM, DISCONTIGMEM and SPARSEMEM. Each architecture defines what +Linux abstracts this diversity using one of the two memory models: +FLATMEM and SPARSEMEM. Each architecture defines what memory models it supports, what the default memory model is and whether it is possible to manually override that default. -.. note:: - At time of this writing, DISCONTIGMEM is considered deprecated, - although it is still in use by several architectures. - All the memory models track the status of physical page frames using struct page arranged in one or more arrays. @@ -63,43 +59,6 @@ straightforward: `PFN - ARCH_PFN_OFFSET` is an index to the The `ARCH_PFN_OFFSET` defines the first page frame number for systems with physical memory starting at address different from 0. -DISCONTIGMEM -============ - -The DISCONTIGMEM model treats the physical memory as a collection of -`nodes` similarly to how Linux NUMA support does. For each node Linux -constructs an independent memory management subsystem represented by -`struct pglist_data` (or `pg_data_t` for short). Among other -things, `pg_data_t` holds the `node_mem_map` array that maps -physical pages belonging to that node. The `node_start_pfn` field of -`pg_data_t` is the number of the first page frame belonging to that -node. - -The architecture setup code should call :c:func:`free_area_init_node` for -each node in the system to initialize the `pg_data_t` object and its -`node_mem_map`. - -Every `node_mem_map` behaves exactly as FLATMEM's `mem_map` - -every physical page frame in a node has a `struct page` entry in the -`node_mem_map` array. When DISCONTIGMEM is enabled, a portion of the -`flags` field of the `struct page` encodes the node number of the -node hosting that page. - -The conversion between a PFN and the `struct page` in the -DISCONTIGMEM model became slightly more complex as it has to determine -which node hosts the physical page and which `pg_data_t` object -holds the `struct page`. - -Architectures that support DISCONTIGMEM provide :c:func:`pfn_to_nid` -to convert PFN to the node number. The opposite conversion helper -:c:func:`page_to_nid` is generic as it uses the node number encoded in -page->flags. - -Once the node number is known, the PFN can be used to index -appropriate `node_mem_map` array to access the `struct page` and -the offset of the `struct page` from the `node_mem_map` plus -`node_start_pfn` is the PFN of that page. - SPARSEMEM =========