If two threads try to flush dirty pages in different inodes respectively,
f2fs_write_data_pages() will produce WRITE and WRITE_SYNC one at a time,
resulting in a lot of 4KB seperated IOs.
So, this patch gives higher priority to WB_SYNC_ALL IOs and gathers write
IOs with a big WRITE_SYNC'ed bio.
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
---
fs/f2fs/data.c | 15 +++++++++++++--
fs/f2fs/f2fs.h | 3 +++
fs/f2fs/super.c | 2 ++
3 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 8f36080b47c4..b1cac6d85bcb 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1605,8 +1605,10 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
last_idx = page->index;
}
- if (--wbc->nr_to_write <= 0 &&
- wbc->sync_mode == WB_SYNC_NONE) {
+ /* give a priority to WB_SYNC threads */
+ if ((atomic_read(&F2FS_M_SB(mapping)->wb_sync_req) ||
+ --wbc->nr_to_write <= 0) &&
+ wbc->sync_mode == WB_SYNC_NONE) {
done = 1;
break;
}
@@ -1662,9 +1664,18 @@ static int f2fs_write_data_pages(struct address_space *mapping,
trace_f2fs_writepages(mapping->host, wbc, DATA);
+ /* to avoid spliting IOs due to mixed WB_SYNC_ALL and WB_SYNC_NONE */
+ if (wbc->sync_mode == WB_SYNC_ALL)
+ atomic_inc(&sbi->wb_sync_req);
+ else if (atomic_read(&sbi->wb_sync_req))
+ goto skip_write;
+
blk_start_plug(&plug);
ret = f2fs_write_cache_pages(mapping, wbc);
blk_finish_plug(&plug);
+
+ if (wbc->sync_mode == WB_SYNC_ALL)
+ atomic_dec(&sbi->wb_sync_req);
/*
* if some pages were truncated, we cannot guarantee its mapping->host
* to detect pending bios.
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 32d6f674c114..fd39db681226 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -888,6 +888,9 @@ struct f2fs_sb_info {
/* # of allocated blocks */
struct percpu_counter alloc_valid_block_count;
+ /* writeback control */
+ atomic_t wb_sync_req; /* count # of WB_SYNC threads */
+
/* valid inode count */
struct percpu_counter total_valid_inode_count;
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 2d78f3c76d18..cb65e6d0d275 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1566,6 +1566,8 @@ static void init_sb_info(struct f2fs_sb_info *sbi)
for (i = 0; i < NR_COUNT_TYPE; i++)
atomic_set(&sbi->nr_pages[i], 0);
+ atomic_set(&sbi->wb_sync_req, 0);
+
INIT_LIST_HEAD(&sbi->s_list);
mutex_init(&sbi->umount_mutex);
mutex_init(&sbi->wio_mutex[NODE]);
--
2.11.0
