When testing f2fs on an SSD, I found some 128 page IOs followed by 1 page IO were issued by f2fs_write_node_pages. This means that there were some mishandling flows which degrades performance.
Previous f2fs_write_node_pages determines the number of pages to be written, nr_to_write, as follows. 1. The bio_get_nr_vecs returns 129 pages. 2. The bio_alloc makes a room for 128 pages. 3. The initial 128 pages go into one bio. 4. The existing bio is submitted, and a new bio is prepared for the last 1 page. 5. Finally, sync_node_pages submits the last 1 page bio. The problem is from the use of bio_get_nr_vecs, so this patch replace it with max_hw_blocks using queue_max_sectors. Signed-off-by: Jaegeuk Kim <[email protected]> --- fs/f2fs/node.c | 6 ++---- fs/f2fs/segment.c | 2 +- fs/f2fs/segment.h | 11 +++++++++++ 3 files changed, 14 insertions(+), 5 deletions(-) diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c index f14eb7b..7209d63 100644 --- a/fs/f2fs/node.c +++ b/fs/f2fs/node.c @@ -1171,7 +1171,6 @@ static int f2fs_write_node_pages(struct address_space *mapping, struct writeback_control *wbc) { struct f2fs_sb_info *sbi = F2FS_SB(mapping->host->i_sb); - struct block_device *bdev = sbi->sb->s_bdev; long nr_to_write = wbc->nr_to_write; /* First check balancing cached NAT entries */ @@ -1185,10 +1184,9 @@ static int f2fs_write_node_pages(struct address_space *mapping, return 0; /* if mounting is failed, skip writing node pages */ - wbc->nr_to_write = bio_get_nr_vecs(bdev); + wbc->nr_to_write = max_hw_blocks(sbi); sync_node_pages(sbi, 0, wbc); - wbc->nr_to_write = nr_to_write - - (bio_get_nr_vecs(bdev) - wbc->nr_to_write); + wbc->nr_to_write = nr_to_write - (max_hw_blocks(sbi) - wbc->nr_to_write); return 0; } diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 392ccb3..d8e84e4 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -734,7 +734,7 @@ static void submit_write_page(struct f2fs_sb_info *sbi, struct page *page, do_submit_bio(sbi, type, false); alloc_new: if (sbi->bio[type] == NULL) { - sbi->bio[type] = f2fs_bio_alloc(bdev, bio_get_nr_vecs(bdev)); + sbi->bio[type] = f2fs_bio_alloc(bdev, max_hw_blocks(sbi)); sbi->bio[type]->bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr); /* * The end_io will be assigned at the sumbission phase. diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h index 26fc054..062424a 100644 --- a/fs/f2fs/segment.h +++ b/fs/f2fs/segment.h @@ -8,6 +8,8 @@ * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ +#include <linux/blkdev.h> + /* constant macro */ #define NULL_SEGNO ((unsigned int)(~0)) #define NULL_SECNO ((unsigned int)(~0)) @@ -86,6 +88,8 @@ #define SECTOR_FROM_BLOCK(sbi, blk_addr) \ (blk_addr << ((sbi)->log_blocksize - F2FS_LOG_SECTOR_SIZE)) +#define SECTOR_TO_BLOCK(sbi, sectors) \ + (sectors >> ((sbi)->log_blocksize - F2FS_LOG_SECTOR_SIZE)) /* during checkpoint, bio_private is used to synchronize the last bio */ struct bio_private { @@ -624,3 +628,10 @@ static inline bool sec_usage_check(struct f2fs_sb_info *sbi, unsigned int secno) return true; return false; } + +static inline unsigned int max_hw_blocks(struct f2fs_sb_info *sbi) +{ + struct block_device *bdev = sbi->sb->s_bdev; + struct request_queue *q = bdev_get_queue(bdev); + return SECTOR_TO_BLOCK(sbi, queue_max_sectors(q)); +} -- 1.8.1.3.566.gaa39828 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
