From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f198.google.com (mail-qk0-f198.google.com [209.85.220.198]) by kanga.kvack.org (Postfix) with ESMTP id 1ACCB6B000D for ; Thu, 28 Jun 2018 02:29:07 -0400 (EDT) Received: by mail-qk0-f198.google.com with SMTP id s63-v6so4488676qkc.7 for ; Wed, 27 Jun 2018 23:29:07 -0700 (PDT) Received: from mx1.redhat.com (mx3-rdu2.redhat.com. [66.187.233.73]) by mx.google.com with ESMTPS id q19-v6si1154296qtj.132.2018.06.27.23.29.05 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 27 Jun 2018 23:29:06 -0700 (PDT) From: Baoquan He Subject: [PATCH v6 0/5] mm/sparse: Optimize memmap allocation during sparse_init() Date: Thu, 28 Jun 2018 14:28:52 +0800 Message-Id: <20180628062857.29658-1-bhe@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, dave.hansen@intel.com, pagupta@redhat.com, Pavel Tatashin , Oscar Salvador Cc: linux-mm@kvack.org, kirill.shutemov@linux.intel.com, Baoquan He This is v6 post. In sparse_init(), two temporary pointer arrays, usemap_map and map_map are allocated with the size of NR_MEM_SECTIONS. They are used to store each memory section's usemap and mem map if marked as present. In 5-level paging mode, this will cost 512M memory though they will be released at the end of sparse_init(). System with few memory, like kdump kernel which usually only has about 256M, will fail to boot because of allocation failure if CONFIG_X86_5LEVEL=y. In this patchset, optimize the memmap allocation code to only use usemap_map and map_map with the size of nr_present_sections. This makes kdump kernel boot up with normal crashkernel='' setting when CONFIG_X86_5LEVEL=y. The old version can be found below: v5: http://lkml.kernel.org/r/20180627013116.12411-1-bhe@redhat.com v4: http://lkml.kernel.org/r/20180521101555.25610-1-bhe@redhat.com v3: https://lkml.org/lkml/2018/2/27/928 V1 can be found here: https://www.spinics.net/lists/linux-mm/msg144486.html Change log: v5->v6: Oscar found the redundant "struct mem_section *ms" definition and in the old patch 2/4, after deferring the clearing of section_mem_map. Clean them up in this version. Pavel pointed out that allocating memmap together for one node at one time should be a default behaviour for all ARCH-es. And if failed on large memory, it will drop to the fallback to allocate memmap for one section at one time, it shoult not break anything. Add patch 5/5 to remove CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER and clean up the related codes. v4->v5: Improve patch 3/4 log according to Dave's suggestion. Correct the wrong copy&paste of making 'nr_consumed_maps' to 'alloc_usemap_and_memmap' mistakenly which is pointed out by Dave in patch 4/4 code comment. Otherwise, no code change in this version. v3->v4: Improve according to Dave's three concerns which are in patch 0004: Rename variable 'idx_present' to 'nr_consumed_maps' which used to index the memmap and usemap of present sections. Add a check if 'nr_consumed_maps' goes beyond nr_present_sections. Add code comment above the final for_each_present_section_nr() to tell why 'nr_consumed_maps' need be increased in each iteration whether the 'ms->section_mem_map' need cleared or out. v2->v3: Change nr_present_sections as __initdata and add code comment according to Andrew's suggestion. Change the local variable 'i' as idx_present which loops over the present sections, and improve the code. These are suggested by Dave and Pankaj. Add a new patch 0003 which adds a new parameter 'data_unit_size' to function alloc_usemap_and_memmap() in which we will update 'data' to make it point at new position. However its type 'void *' can't give us needed info to do that. Need pass the unit size in. So change code in patch 0004 accordingly. This is a code bug fix found when tested the memory deployed on multiple nodes. v1-v2: Split out the nr_present_sections adding as a single patch for easier reviewing. Rewrite patch log according to Dave's suggestion. Fix code bug in patch 0002 reported by test robot. Baoquan He (5): mm/sparse: Add a static variable nr_present_sections mm/sparsemem: Defer the ms->section_mem_map clearing mm/sparse: Add a new parameter 'data_unit_size' for alloc_usemap_and_memmap mm/sparse: Optimize memmap allocation during sparse_init() mm/sparse: Remove CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER mm/Kconfig | 4 -- mm/sparse-vmemmap.c | 9 ++--- mm/sparse.c | 109 ++++++++++++++++++++++++++++------------------------ 3 files changed, 62 insertions(+), 60 deletions(-) -- 2.13.6