Messages in this thread |  | | From | Baoquan He <> | Subject | [PATCH v3 0/4] mm/sparse: Optimize memmap allocation during sparse_init() | Date | Wed, 28 Feb 2018 11:26:53 +0800 |
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This is v3 post. V1 can be found here: https://www.spinics.net/lists/linux-mm/msg144486.html
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.
Change log: 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 (4): 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-vmemmap.c | 6 +++--- mm/sparse.c | 62 ++++++++++++++++++++++++++++++++++++++--------------- 2 files changed, 48 insertions(+), 20 deletions(-)
-- 2.13.6
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