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authorPaul Burton <paul.burton@imgtec.com>2017-02-23 02:44:53 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-23 03:41:29 +0300
commitb92df1de5d289c0b5d653e72414bf0850b8511e0 (patch)
tree6604acfffcd8f9ca58499f892531bd08dc117fea /mm/memblock.c
parent7f354a548d1cb6bb01b6ee74aee9264aa152f1ec (diff)
downloadlinux-b92df1de5d289c0b5d653e72414bf0850b8511e0.tar.xz
mm: page_alloc: skip over regions of invalid pfns where possible
When using a sparse memory model memmap_init_zone() when invoked with the MEMMAP_EARLY context will skip over pages which aren't valid - ie. which aren't in a populated region of the sparse memory map. However if the memory map is extremely sparse then it can spend a long time linearly checking each PFN in a large non-populated region of the memory map & skipping it in turn. When CONFIG_HAVE_MEMBLOCK_NODE_MAP is enabled, we have sufficient information to quickly discover the next valid PFN given an invalid one by searching through the list of memory regions & skipping forwards to the first PFN covered by the memory region to the right of the non-populated region. Implement this in order to speed up memmap_init_zone() for systems with extremely sparse memory maps. James said "I have tested this patch on a virtual model of a Samurai CPU with a sparse memory map. The kernel boot time drops from 109 to 62 seconds. " Link: http://lkml.kernel.org/r/20161125185518.29885-1-paul.burton@imgtec.com Signed-off-by: Paul Burton <paul.burton@imgtec.com> Tested-by: James Hartley <james.hartley@imgtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memblock.c')
-rw-r--r--mm/memblock.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/mm/memblock.c b/mm/memblock.c
index 7608bc305936..a476d28e0733 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1105,6 +1105,31 @@ void __init_memblock __next_mem_pfn_range(int *idx, int nid,
*out_nid = r->nid;
}
+unsigned long __init_memblock memblock_next_valid_pfn(unsigned long pfn,
+ unsigned long max_pfn)
+{
+ struct memblock_type *type = &memblock.memory;
+ unsigned int right = type->cnt;
+ unsigned int mid, left = 0;
+ phys_addr_t addr = PFN_PHYS(pfn + 1);
+
+ do {
+ mid = (right + left) / 2;
+
+ if (addr < type->regions[mid].base)
+ right = mid;
+ else if (addr >= (type->regions[mid].base +
+ type->regions[mid].size))
+ left = mid + 1;
+ else {
+ /* addr is within the region, so pfn + 1 is valid */
+ return min(pfn + 1, max_pfn);
+ }
+ } while (left < right);
+
+ return min(PHYS_PFN(type->regions[right].base), max_pfn);
+}
+
/**
* memblock_set_node - set node ID on memblock regions
* @base: base of area to set node ID for