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f2fs: modify the number of issued pages to merge IOs

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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 <jaegeuk.kim@samsung.com>
This commit is contained in:
Jaegeuk Kim
2013-04-29 16:58:39 +09:00
parent b743ba78ae
commit ac5d156c78
3 changed files with 14 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files
fs/f2fs/node.c
+2 -4
View File
@@ -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;
}