[PATCH RFC 0/4] optimize memblock_next_valid_pfn() and early_pfn_valid()

[Jia He]

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 optimized the memblock_next_valid_pfn()
Patch 2~4 optimized the early_pfn_valid(), I have to split it into parts
because the changes are located across subsystems.

I tested the pfn steping up 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

Jia He (4):
  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             | 19 ++++++++++++++++++-
 arch/x86/include/asm/mmzone_32.h |  2 +-
 include/linux/memblock.h         |  3 ++-
 include/linux/mmzone.h           | 12 +++++++++---
 mm/memblock.c                    | 35 +++++++++++++++++++++++++++++++----
 mm/page_alloc.c                  |  5 +++--
 7 files changed, 66 insertions(+), 13 deletions(-)

-- 
2.7.4