Vlastimil Babka pointed out that an unlikely annotation in free_pages_prepare shrinks stack usage by moving compound handling to the end of the function.
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-30 (-30) function old new delta free_pages_prepare 771 741 -30 It's also consistent with the buffered_rmqueue path. This is a fix to the mmotm patch mm-page_alloc-only-check-pagecompound-for-high-order-pages.patch. Suggested-by: Vlastimil Babka <[email protected]> Signed-off-by: Mel Gorman <[email protected]> --- mm/page_alloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 1da56779f8fa..d8383750bd43 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1003,7 +1003,7 @@ static bool free_pages_prepare(struct page *page, unsigned int order) * Check tail pages before head page information is cleared to * avoid checking PageCompound for order-0 pages. */ - if (order) { + if (unlikely(order)) { bool compound = PageCompound(page); int i; -- 2.6.4
