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From:   Jia He <hejianet@gmail.com>
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        Jia He <jia.he@hxt-semitech.com>
Subject: [PATCH v10 5/6] mm/memblock: introduce pfn_valid_region()
Date:   Fri,  6 Jul 2018 16:14:19 +0800
Message-Id: <1530864860-7671-6-git-send-email-hejianet@gmail.com>
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From: Jia He <jia.he@hxt-semitech.com>

Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns
where possible") optimized the loop in memmap_init_zone(). But there is
still some room for improvement.
E.g. in early_pfn_valid(), we can record the last returned memblock region.
If current pfn and last pfn are in the same memory region, we needn't do
the unnecessary binary searches because memblock_is_nomap is the same
result for whole memory region.

Signed-off-by: Jia He <jia.he@hxt-semitech.com>
---
 mm/memblock.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/mm/memblock.c b/mm/memblock.c
index c783b1a..274bd9f 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1188,6 +1188,30 @@ ulong __init_memblock memblock_next_valid_pfn(ulong pfn)
 	return PHYS_PFN(regions[early_region_idx].base);
 }
 EXPORT_SYMBOL(memblock_next_valid_pfn);
+
+int pfn_valid_region(ulong pfn)
+{
+	ulong start_pfn, end_pfn;
+	struct memblock_type *type = &memblock.memory;
+	struct memblock_region *regions = type->regions;
+
+	if (early_region_idx != -1) {
+		start_pfn = PFN_DOWN(regions[early_region_idx].base);
+		end_pfn = PFN_DOWN(regions[early_region_idx].base +
+					regions[early_region_idx].size);
+
+		if (pfn >= start_pfn && pfn < end_pfn)
+			return !memblock_is_nomap(
+					&regions[early_region_idx]);
+	}
+
+	early_region_idx = memblock_search_pfn_regions(pfn);
+	if (early_region_idx == -1)
+		return false;
+
+	return !memblock_is_nomap(&regions[early_region_idx]);
+}
+EXPORT_SYMBOL(pfn_valid_region);
 #endif /*CONFIG_HAVE_MEMBLOCK_PFN_VALID*/
 
 static phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
-- 
1.8.3.1