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authorEric Dumazet <dada1@cosmosbay.com>2007-07-15 23:38:05 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-16 09:05:35 -0700
commit1037b83bd04e31449dc9323f1e8ddada4264ef66 (patch)
treeaad6be88185e675503847d3cf43a257ceb93d0f9 /mm
parentb92151bab91ef906378d3e0e7128d55dd641e966 (diff)
MM: alloc_large_system_hash() can free some memory for non power-of-two bucketsize
alloc_large_system_hash() is called at boot time to allocate space for several large hash tables. Lately, TCP hash table was changed and its bucketsize is not a power-of-two anymore. On most setups, alloc_large_system_hash() allocates one big page (order > 0) with __get_free_pages(GFP_ATOMIC, order). This single high_order page has a power-of-two size, bigger than the needed size. We can free all pages that wont be used by the hash table. On a 1GB i386 machine, this patch saves 128 KB of LOWMEM memory. TCP established hash table entries: 32768 (order: 6, 393216 bytes) Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/page_alloc.c15
1 files changed, 15 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 092b2d8f2f0c..8dadda6e1feb 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3584,6 +3584,21 @@ void *__init alloc_large_system_hash(const char *tablename,
for (order = 0; ((1UL << order) << PAGE_SHIFT) < size; order++)
;
table = (void*) __get_free_pages(GFP_ATOMIC, order);
+ /*
+ * If bucketsize is not a power-of-two, we may free
+ * some pages at the end of hash table.
+ */
+ if (table) {
+ unsigned long alloc_end = (unsigned long)table +
+ (PAGE_SIZE << order);
+ unsigned long used = (unsigned long)table +
+ PAGE_ALIGN(size);
+ split_page(virt_to_page(table), order);
+ while (used < alloc_end) {
+ free_page(used);
+ used += PAGE_SIZE;
+ }
+ }
}
} while (!table && size > PAGE_SIZE && --log2qty);