On a 104 thread, 2 socket Skylake system, Intel report a 4.7% performance reduction with will-it-scale page_fault2. This was due to reducing the size of the batch from 32 to 15. Increasing the folio batch size from 15 to 31 gives a performance increase of 12.5% relative to the original, or 17.2% relative to the reduced performance commit. The penalty of this commit is an additional 128 bytes of stack usage. Six folio_batches are also allocated from percpu memory in cpu_fbatches so that will be an additional 768 bytes of percpu memory (per CPU). Tim Chen originally submitted a patch like this in 2020: https://lore.kernel.org/linux-mm/d1cc9f12a8ad6c2a52cb600d93b06b064f2bbc57.1593205965.git.tim.c.chen@xxxxxxxxxxxxxxx/ Tested-by: Yujie Liu <yujie.liu@xxxxxxxxx> Fixes: 99fbb6bfc16f ("mm: make folios_put() the basis of release_pages()") Reported-by: kernel test robot <oliver.sang@xxxxxxxxx> Closes: https://lore.kernel.org/oe-lkp/202403151058.7048f6a8-oliver.sang@xxxxxxxxx Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> --- include/linux/pagevec.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/pagevec.h b/include/linux/pagevec.h index fcc06c300a72..5d3a0cccc6bf 100644 --- a/include/linux/pagevec.h +++ b/include/linux/pagevec.h @@ -11,8 +11,8 @@ #include <linux/types.h> -/* 15 pointers + header align the folio_batch structure to a power of two */ -#define PAGEVEC_SIZE 15 +/* 31 pointers + header align the folio_batch structure to a power of two */ +#define PAGEVEC_SIZE 31 struct folio; -- 2.43.0
