The patch titled
Subject: mm: page_alloc: skip over regions of invalid pfns where possible
has been added to the -mm tree. Its filename is
mm-page_alloc-skip-over-regions-of-invalid-pfns-where-possible.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-page_alloc-skip-over-regions-of-invalid-pfns-where-possible.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-skip-over-regions-of-invalid-pfns-where-possible.patch
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------------------------------------------------------
From: Paul Burton <paul.burton@xxxxxxxxxx>
Subject: 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.
Link: http://lkml.kernel.org/r/20161125185518.29885-1-paul.burton@xxxxxxxxxx
Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx>
Cc: James Hartley <james.hartley@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memblock.h | 1 +
mm/memblock.c | 25 +++++++++++++++++++++++++
mm/page_alloc.c | 11 ++++++++++-
3 files changed, 36 insertions(+), 1 deletion(-)
diff -puN include/linux/memblock.h~mm-page_alloc-skip-over-regions-of-invalid-pfns-where-possible include/linux/memblock.h
--- a/include/linux/memblock.h~mm-page_alloc-skip-over-regions-of-invalid-pfns-where-possible
+++ a/include/linux/memblock.h
@@ -203,6 +203,7 @@ int memblock_search_pfn_nid(unsigned lon
unsigned long *end_pfn);
void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn,
unsigned long *out_end_pfn, int *out_nid);
+unsigned long memblock_next_valid_pfn(unsigned long pfn, unsigned long max_pfn);
/**
* for_each_mem_pfn_range - early memory pfn range iterator
diff -puN mm/memblock.c~mm-page_alloc-skip-over-regions-of-invalid-pfns-where-possible mm/memblock.c
--- a/mm/memblock.c~mm-page_alloc-skip-over-regions-of-invalid-pfns-where-possible
+++ a/mm/memblock.c
@@ -1105,6 +1105,31 @@ void __init_memblock __next_mem_pfn_rang
*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
diff -puN mm/page_alloc.c~mm-page_alloc-skip-over-regions-of-invalid-pfns-where-possible mm/page_alloc.c
--- a/mm/page_alloc.c~mm-page_alloc-skip-over-regions-of-invalid-pfns-where-possible
+++ a/mm/page_alloc.c
@@ -5080,8 +5080,17 @@ void __meminit memmap_init_zone(unsigned
if (context != MEMMAP_EARLY)
goto not_early;
- if (!early_pfn_valid(pfn))
+ if (!early_pfn_valid(pfn)) {
+#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
+ /*
+ * Skip to the pfn preceding the next valid one (or
+ * end_pfn), such that we hit a valid pfn (or end_pfn)
+ * on our next iteration of the loop.
+ */
+ pfn = memblock_next_valid_pfn(pfn, end_pfn) - 1;
+#endif
continue;
+ }
if (!early_pfn_in_nid(pfn, nid))
continue;
if (!update_defer_init(pgdat, pfn, end_pfn, &nr_initialised))
_
Patches currently in -mm which might be from paul.burton@xxxxxxxxxx are
mm-page_alloc-skip-over-regions-of-invalid-pfns-where-possible.patch
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