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authorLinus Torvalds <torvalds@linux-foundation.org>2011-07-23 04:04:18 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2011-07-23 04:04:18 +0400
commit9e39264ed4f687251632c0a6f4a70c2e51719662 (patch)
tree27651ca028328ac5e7b5a030312ad113b6cb8b2b /mm
parentdc43d9fa73d82083656fb9c02f4823bcdcfb9f91 (diff)
parent1e01979c8f502ac13e3cdece4f38712c5944e6e8 (diff)
downloadlinux-9e39264ed4f687251632c0a6f4a70c2e51719662.tar.xz
Merge branch 'x86-numa-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-numa-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, numa: Implement pfn -> nid mapping granularity check x86, mm: s/PAGES_PER_ELEMENT/PAGES_PER_SECTION/
Diffstat (limited to 'mm')
-rw-r--r--mm/page_alloc.c54
1 files changed, 54 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4e8985acdab8..9119faae6e6a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4585,6 +4585,60 @@ void __init sort_node_map(void)
cmp_node_active_region, NULL);
}
+/**
+ * node_map_pfn_alignment - determine the maximum internode alignment
+ *
+ * This function should be called after node map is populated and sorted.
+ * It calculates the maximum power of two alignment which can distinguish
+ * all the nodes.
+ *
+ * For example, if all nodes are 1GiB and aligned to 1GiB, the return value
+ * would indicate 1GiB alignment with (1 << (30 - PAGE_SHIFT)). If the
+ * nodes are shifted by 256MiB, 256MiB. Note that if only the last node is
+ * shifted, 1GiB is enough and this function will indicate so.
+ *
+ * This is used to test whether pfn -> nid mapping of the chosen memory
+ * model has fine enough granularity to avoid incorrect mapping for the
+ * populated node map.
+ *
+ * Returns the determined alignment in pfn's. 0 if there is no alignment
+ * requirement (single node).
+ */
+unsigned long __init node_map_pfn_alignment(void)
+{
+ unsigned long accl_mask = 0, last_end = 0;
+ int last_nid = -1;
+ int i;
+
+ for_each_active_range_index_in_nid(i, MAX_NUMNODES) {
+ int nid = early_node_map[i].nid;
+ unsigned long start = early_node_map[i].start_pfn;
+ unsigned long end = early_node_map[i].end_pfn;
+ unsigned long mask;
+
+ if (!start || last_nid < 0 || last_nid == nid) {
+ last_nid = nid;
+ last_end = end;
+ continue;
+ }
+
+ /*
+ * Start with a mask granular enough to pin-point to the
+ * start pfn and tick off bits one-by-one until it becomes
+ * too coarse to separate the current node from the last.
+ */
+ mask = ~((1 << __ffs(start)) - 1);
+ while (mask && last_end <= (start & (mask << 1)))
+ mask <<= 1;
+
+ /* accumulate all internode masks */
+ accl_mask |= mask;
+ }
+
+ /* convert mask to number of pages */
+ return ~accl_mask + 1;
+}
+
/* Find the lowest pfn for a node */
static unsigned long __init find_min_pfn_for_node(int nid)
{