From a7fdffbd3ea4b3cc2993af006bde38a423b38b72 Mon Sep 17 00:00:00 2001 From: Jaegeuk Kim Date: Fri, 18 Jan 2013 14:54:13 +0900 Subject: [PATCH] f2fs: avoid issuing small bios due to several dirty node pages If some small bios of dirty node pages are supposed to be issued during the sequential data writes, there-in well-produced consecutive data bios are able to be split by the small node bios, resulting in performance degradation. So, let's collect a number of dirty node pages until reaching a threshold. And, by default, I set the threshold as 2MB, a segment size. This improves sequential write performance on i5, 512GB SSD (830 w/ SATA2) as follows. Before: 231 MB/s -> After: 255 MB/s Signed-off-by: Jaegeuk Kim Reviewed-by: Namjae Jeon --- fs/f2fs/node.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c index f177c018745..9bda63c9c16 100644 --- a/fs/f2fs/node.c +++ b/fs/f2fs/node.c @@ -1124,6 +1124,12 @@ static int f2fs_write_node_page(struct page *page, return 0; } +/* + * It is very important to gather dirty pages and write at once, so that we can + * submit a big bio without interfering other data writes. + * Be default, 512 pages (2MB), a segment size, is quite reasonable. + */ +#define COLLECT_DIRTY_NODES 512 static int f2fs_write_node_pages(struct address_space *mapping, struct writeback_control *wbc) { @@ -1131,17 +1137,16 @@ static int f2fs_write_node_pages(struct address_space *mapping, struct block_device *bdev = sbi->sb->s_bdev; long nr_to_write = wbc->nr_to_write; - if (wbc->for_kupdate) - return 0; - - if (get_pages(sbi, F2FS_DIRTY_NODES) == 0) - return 0; - + /* First check balancing cached NAT entries */ if (try_to_free_nats(sbi, NAT_ENTRY_PER_BLOCK)) { write_checkpoint(sbi, false, false); return 0; } + /* collect a number of dirty node pages and write together */ + if (get_pages(sbi, F2FS_DIRTY_NODES) < COLLECT_DIRTY_NODES) + return 0; + /* if mounting is failed, skip writing node pages */ wbc->nr_to_write = bio_get_nr_vecs(bdev); sync_node_pages(sbi, 0, wbc);