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Subject[PATCH v2 0/5] optimize memblock_next_valid_pfn() and early_pfn_valid()
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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 when CONFIG_HAVE_ARCH_PFN_VALID
is enabled
Patch 2 optimizes the memblock_next_valid_pfn()
Patch 3~5 optimizes the early_pfn_valid(), I have to split it into parts
because the changes are located across subsystems.

I tested the pfn loop process in memmap_init(), the same as before.
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:
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() when
CONFIG_HAVE_ARCH_PFN_VALID is enable
mm: page_alloc: reduce unnecessary binary search in
memblock_next_valid_pfn()
mm/memblock: introduce memblock_search_pfn_regions()
arm64: introduce pfn_valid_region()
mm: page_alloc: reduce unnecessary binary search in early_pfn_valid()

arch/arm64/include/asm/page.h | 3 ++-
arch/arm64/mm/init.c | 25 ++++++++++++++++++-
arch/x86/include/asm/mmzone_32.h | 2 +-
include/linux/memblock.h | 6 +++++
include/linux/mmzone.h | 12 ++++++---
mm/memblock.c | 53 ++++++++++++++++++++++++++++++++++++++++
mm/page_alloc.c | 12 ++++++++-
7 files changed, 106 insertions(+), 7 deletions(-)

--
2.7.4

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