From c718379b6b0954a04a153d7e5dc8b3136a301ee6 Mon Sep 17 00:00:00 2001 From: Jaegeuk Kim Date: Wed, 24 Apr 2013 13:19:56 +0900 Subject: f2fs: give a chance to merge IOs by IO scheduler Previously, background GC submits many 4KB read requests to load victim blocks and/or its (i)node blocks. ... f2fs_gc : f2fs_readpage: ino = 1, page_index = 0xb61, blkaddr = 0x3b964ed f2fs_gc : block_rq_complete: 8,16 R () 499854968 + 8 [0] f2fs_gc : f2fs_readpage: ino = 1, page_index = 0xb6f, blkaddr = 0x3b964ee f2fs_gc : block_rq_complete: 8,16 R () 499854976 + 8 [0] f2fs_gc : f2fs_readpage: ino = 1, page_index = 0xb79, blkaddr = 0x3b964ef f2fs_gc : block_rq_complete: 8,16 R () 499854984 + 8 [0] ... However, by the fact that many IOs are sequential, we can give a chance to merge the IOs by IO scheduler. In order to do that, let's use blk_plug. ... f2fs_gc : f2fs_iget: ino = 143 f2fs_gc : f2fs_readpage: ino = 143, page_index = 0x1c6, blkaddr = 0x2e6ee f2fs_gc : f2fs_iget: ino = 143 f2fs_gc : f2fs_readpage: ino = 143, page_index = 0x1c7, blkaddr = 0x2e6ef : block_rq_complete: 8,16 R () 1519616 + 8 [0] : block_rq_complete: 8,16 R () 1519848 + 8 [0] : block_rq_complete: 8,16 R () 1520432 + 96 [0] : block_rq_complete: 8,16 R () 1520536 + 104 [0] : block_rq_complete: 8,16 R () 1521008 + 112 [0] : block_rq_complete: 8,16 R () 1521440 + 152 [0] : block_rq_complete: 8,16 R () 1521688 + 144 [0] : block_rq_complete: 8,16 R () 1522128 + 192 [0] : block_rq_complete: 8,16 R () 1523256 + 328 [0] ... Note that this issue should be addressed in checkpoint, and some readahead flows too. Reviewed-by: Namjae Jeon Signed-off-by: Jaegeuk Kim --- fs/f2fs/checkpoint.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'fs/f2fs/checkpoint.c') diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c index f54b83b4d90b..590ea50c80a7 100644 --- a/fs/f2fs/checkpoint.c +++ b/fs/f2fs/checkpoint.c @@ -549,6 +549,10 @@ static void block_operations(struct f2fs_sb_info *sbi) .nr_to_write = LONG_MAX, .for_reclaim = 0, }; + struct blk_plug plug; + + blk_start_plug(&plug); + retry_flush_dents: mutex_lock_all(sbi); @@ -571,6 +575,7 @@ retry_flush_nodes: sync_node_pages(sbi, 0, &wbc); goto retry_flush_nodes; } + blk_finish_plug(&plug); } static void unblock_operations(struct f2fs_sb_info *sbi) -- cgit v1.2.3