From patchwork Fri Jun 4 06:49:14 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mike Rapoport X-Patchwork-Id: 12298885 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=-16.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 D0A54C47083 for ; Fri, 4 Jun 2021 06:51:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7DCA8613EC for ; Fri, 4 Jun 2021 06:51:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7DCA8613EC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2380C6B006C; Fri, 4 Jun 2021 02:51:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 20FFA6B006E; Fri, 4 Jun 2021 02:51:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 061F76B0070; Fri, 4 Jun 2021 02:51:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0043.hostedemail.com [216.40.44.43]) by kanga.kvack.org (Postfix) with ESMTP id C71E46B006C for ; Fri, 4 Jun 2021 02:51:34 -0400 (EDT) Received: from smtpin19.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 6A052F049 for ; Fri, 4 Jun 2021 06:51:34 +0000 (UTC) X-FDA: 78215120508.19.3B363D7 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf07.hostedemail.com (Postfix) with ESMTP id DA17AA0021E8 for ; Fri, 4 Jun 2021 06:50:12 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 2A62161413; Fri, 4 Jun 2021 06:50:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622789416; bh=ABj3dtzcvKeBeFBwlP7EY29yWmF1bk7z4ehtK6n5siY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mirhPcESlyml6qeJF+3PmzjJx7pB3jVvzPq4qlQg/cZIoGi8aioFbqYOS/bxdBkCP Xs/qVpOHliG5ABDPA5c5+b9SOOfuQhoOVZjMEPJcXE3kcO87oRDXIB2TVVCw7tEtBl zWNbUZLbIEudT9bbH4CpwhJ0Rka6vnjadh7KXezuLyxU8Gy6kgJHj5oagrzqDk147m Ovce+6DO0QEMb/QcALeMLZnWz5AoKteD9V/PIHoCAt2JvSEGWROKn7PBeMPmrxmjOH V6mqUOpTOk7SQWLiAAY4D4TAOeGLjZ5YZ/637bWUG4jQdfv+t7FCGwh3Jc9huvqjv/ Ucn78M19+qN6w== 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 v2 7/9] docs: remove description of DISCONTIGMEM Date: Fri, 4 Jun 2021 09:49:14 +0300 Message-Id: <20210604064916.26580-8-rppt@kernel.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20210604064916.26580-1-rppt@kernel.org> References: <20210604064916.26580-1-rppt@kernel.org> MIME-Version: 1.0 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: DA17AA0021E8 X-Stat-Signature: t7q9aufr3p6ckbg98rs7kihhf6go9n4r Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=mirhPcES; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf07.hostedemail.com: domain of rppt@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=rppt@kernel.org X-HE-Tag: 1622789412-516101 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 =========