Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns where possible") tried to optimize the loop in memmap_init_zone(). But there is still some room for improvement. Patch 1 remain the memblock_next_valid_pfn on arm and arm64 Patch 2 optimizes the memblock_next_valid_pfn() Patch 3~5 optimizes the early_pfn_valid() As for the performance improvement, after this set, I can see the time overhead of memmap_init() is reduced from 41313 us to 24345 us in my armv8a server(QDF2400 with 96G memory). Attached the memblock region information in my server. [ 86.956758] Zone ranges: [ 86.959452] DMA [mem 0x0000000000200000-0x00000000ffffffff] [ 86.966041] Normal [mem 0x0000000100000000-0x00000017ffffffff] [ 86.972631] Movable zone start for each node [ 86.977179] Early memory node ranges [ 86.980985] node 0: [mem 0x0000000000200000-0x000000000021ffff] [ 86.987666] node 0: [mem 0x0000000000820000-0x000000000307ffff] [ 86.994348] node 0: [mem 0x0000000003080000-0x000000000308ffff] [ 87.001029] node 0: [mem 0x0000000003090000-0x00000000031fffff] [ 87.007710] node 0: [mem 0x0000000003200000-0x00000000033fffff] [ 87.014392] node 0: [mem 0x0000000003410000-0x000000000563ffff] [ 87.021073] node 0: [mem 0x0000000005640000-0x000000000567ffff] [ 87.027754] node 0: [mem 0x0000000005680000-0x00000000056dffff] [ 87.034435] node 0: [mem 0x00000000056e0000-0x00000000086fffff] [ 87.041117] node 0: [mem 0x0000000008700000-0x000000000871ffff] [ 87.047798] node 0: [mem 0x0000000008720000-0x000000000894ffff] [ 87.054479] node 0: [mem 0x0000000008950000-0x0000000008baffff] [ 87.061161] node 0: [mem 0x0000000008bb0000-0x0000000008bcffff] [ 87.067842] node 0: [mem 0x0000000008bd0000-0x0000000008c4ffff] [ 87.074524] node 0: [mem 0x0000000008c50000-0x0000000008e2ffff] [ 87.081205] node 0: [mem 0x0000000008e30000-0x0000000008e4ffff] [ 87.087886] node 0: [mem 0x0000000008e50000-0x0000000008fcffff] [ 87.094568] node 0: [mem 0x0000000008fd0000-0x000000000910ffff] [ 87.101249] node 0: [mem 0x0000000009110000-0x00000000092effff] [ 87.107930] node 0: [mem 0x00000000092f0000-0x000000000930ffff] [ 87.114612] node 0: [mem 0x0000000009310000-0x000000000963ffff] [ 87.121293] node 0: [mem 0x0000000009640000-0x000000000e61ffff] [ 87.127975] node 0: [mem 0x000000000e620000-0x000000000e64ffff] [ 87.134657] node 0: [mem 0x000000000e650000-0x000000000fffffff] [ 87.141338] node 0: [mem 0x0000000010800000-0x0000000017feffff] [ 87.148019] node 0: [mem 0x000000001c000000-0x000000001c00ffff] [ 87.154701] node 0: [mem 0x000000001c010000-0x000000001c7fffff] [ 87.161383] node 0: [mem 0x000000001c810000-0x000000007efbffff] [ 87.168064] node 0: [mem 0x000000007efc0000-0x000000007efdffff] [ 87.174746] node 0: [mem 0x000000007efe0000-0x000000007efeffff] [ 87.181427] node 0: [mem 0x000000007eff0000-0x000000007effffff] [ 87.188108] node 0: [mem 0x000000007f000000-0x00000017ffffffff] [ 87.194791] Initmem setup node 0 [mem 0x0000000000200000-0x00000017ffffffff] Without this patchset: [ 117.106153] Initmem setup node 0 [mem 0x0000000000200000-0x00000017ffffffff] [ 117.113677] before memmap_init [ 117.118195] after memmap_init >>> memmap_init takes 4518 us [ 117.121446] before memmap_init [ 117.154992] after memmap_init >>> memmap_init takes 33546 us [ 117.158241] before memmap_init [ 117.161490] after memmap_init >>> memmap_init takes 3249 us >>> totally takes 41313 us With this patchset: [ 87.194791] Initmem setup node 0 [mem 0x0000000000200000-0x00000017ffffffff] [ 87.202314] before memmap_init [ 87.206164] after memmap_init >>> memmap_init takes 3850 us [ 87.209416] before memmap_init [ 87.226662] after memmap_init >>> memmap_init takes 17246 us [ 87.229911] before memmap_init [ 87.233160] after memmap_init >>> memmap_init takes 3249 us >>> totally takes 24345 us Changelog: V6: - simplify the codes, move arm/arm64 common codes to one file. - refine patches as suggested by Danial Vacek and Ard Biesheuvel V5: - further refining as suggested by Danial Vacek. Make codes arm/arm64 more arch specific V4: - refine patches as suggested by Danial Vacek and Wei Yang - optimized on arm besides arm64 V3: - fix 2 issues reported by kbuild test robot V2: - rebase to mmotm latest - remain memblock_next_valid_pfn on arm64 - refine memblock_search_pfn_regions and pfn_valid_region Jia He (5): mm: page_alloc: remain memblock_next_valid_pfn() on arm and arm64 arm: arm64: page_alloc: reduce unnecessary binary search in memblock_next_valid_pfn() mm/memblock: introduce memblock_search_pfn_regions() arm: arm64: introduce pfn_valid_region() mm: page_alloc: reduce unnecessary binary search in early_pfn_valid() arch/arm/mm/init.c | 1 + arch/arm64/mm/init.c | 1 + include/linux/arm96_common.h | 76 ++++++++++++++++++++++++++++++++++++++++++++ include/linux/memblock.h | 2 ++ include/linux/mmzone.h | 18 ++++++++++- mm/memblock.c | 9 ++++++ mm/page_alloc.c | 2 +- 7 files changed, 107 insertions(+), 2 deletions(-) create mode 100644 include/linux/arm96_common.h -- 2.7.4