On 06/27/18 at 09:31am, Baoquan He wrote: > This is v4 post. V3 can be found here: > https://lkml.org/lkml/2018/2/27/928 Sorry, forgot updating this part. This is v5 post, v4 can be found here: http://lkml.kernel.org/r/20180521101555.25610-1-bhe@xxxxxxxxxx > > 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: > 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 (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 | 72 +++++++++++++++++++++++++++++++++++++++++------------ > 2 files changed, 59 insertions(+), 19 deletions(-) > > -- > 2.13.6 >
